I have a lvl 50 kin/rad that is one of my favorite builds - partly because of the theme - The CoTs have Stolen my Clothes - and partly because it is a fun build. I agree with the above commenters that it is hardly a scrapfender due to a lack of melee attacks/defense, but it can very much be played like an Offender. Kin is one of the most Flexible Powersets - so I can be very defensively team oriented, very offensively team oriented, or can solo offensively, depending on who I am playing with and how I am feeling. Some tactics:
First and Foremost - Always carry Break Frees. Always Always Always. You have No defense to holds/stuns/sleeps etc, and many of your "defensive" powers (your buffs) still target NPCs, so you often draw aggro. At high levels, Everything has holds - Carnie Illusionists and Dark Ring Mistresses, Ritki Mezzers, every Malta it seems, EXPEcially Tac Ops Commanders - everything holds, stuns, sleeps, etc. I've tried many powers to cover this - I have CJ, Acro, Manuevers, Dark Embrace and Oppressive Gloom - and I have come to the conclusion that the only thing you can do is break free and retoggle and then recover. But you have to have lots of Break Frees. I delete other Insps and buy them in between every mission it seems. I don't know if Tough / Weave does anything about holds/stuns/sleeps, but I don't think so.
Second, when you are soloing, Lead with the Stunners - Cosmic Burst is an Awesome stun power, and with recharge and a stun enhancements, you can perma stun most bosses. I also have Oppressive Gloom from the Dark Mastery Epic Pool, and this stuns minion level meleers around you relatively reliably. I usually solo on Unyielding, which gives me mostly groups of four yellow minions and an orange lieut, or two orange lieuts and a yellow minion. I try to start out fights by stunning whatever can hold me the most. That isn't always the boss, but often is. For instance, always stun sappers first, but you definitely need to stun the Gunslingers and Tac Ops guys too, and also the Operations Officers - I hate fighting Malta with this toon because they All seem to carry stuns/holds. But anyway, you can usually stun one and, if you are in the group of five, use your AOEs to kill off the minions, while Cosmic Bursting the Lieut. Or, in the group of three, you can juggle stun between the Lieuts until they are gone and then finish off the minion. But when soloing, stun things.
Third, I think it is important to have Stamina even though you have transference. The reason is that you are not always using Transference on an enemy near you. When you are soloing you will, and when you are taking on some of the Offensive responsibilities on your team, you will. But, and this happens often, when you are mostly buffing other offensive ATs, you won't always, or even most of the time, be in range for your own transference. And you shouldn't be - it isn't there to save you in those instances, it is there to keep the Scrappers and Tanks going. And your build, at least my build, is a Toggle fest, trying to eek out Some defense. And your key powers in those situations are Endurance heavy - like Fulcrum Shift, (ironically) Transference, and Speed Boost (because you have to use it so often). Basically you are much Busier than other Defenders when you are on Team Buffing/Defense, so you run through End quickly, and Stamina makes an Enormous difference for those situations.
Fourth - You can play very offensively. If your team doesn't have a lot of damage output, you can add a lot. Kin and Rad work well together here, with a lot of AOEs that benefit alot from Siphon Power and Fulcrum Shift. In these instances, you need to make sure that you go into the initial mob with whoever is taking the Alpha, so that you are in range to get the most of your Fulcrum Shift. Then Irradiate and Neutron Bomb, and line up Electron Haze cones. You can pour out substantial damage - not scrapper or Blaster damage, but if you had enough of them on your team, you wouldn't need to be taking over dps responsibilities, would you? In these situations, you have to follow quickly with Transfusion and Transference, since you will be taking a lot of aggro, and because your Rad attacks use Even More endurance than your Kin powers. But FS, Irrad, Transfusion, Transference, Neutron Bomb, Haze, Transfusion, Irrad, Neutron Bomb Haze - that can do a lot of AOE damage before FS runs out. BTW, if you are soloing in PI, groups of 8-10 Jaegers are great for this as well, because They don't have holds. Don't try the same thing with the Possessed Scientists or Malta Groups hanging around. Very different results.
If you are on a team with a lot of Damage Dealers, you can afford to be more defensive. You were probably invited on to that team for your buffs/debuffs, so fill that role. SB as often to as many people as you can. FS every mob from a distance once both the Tank and any/all scrappers are in the mob. Spam Transf/Transf, and even siphon power and speed from the bosses/AVs/EBs/Monsters. You will often find that you don't have much time to throw in your Neutron Bombs or Irrads - everyone is killing too quickly when they are on SB, FS and don't have to worry about green or blue bars.
This is both true in large and small teams. A Scrapper paired with a Kin/Rad is going to be running Top Speed through your missions with his or her own personal SB/FSer. They will be happy as a clams. In larger teams, with multiple scrappers and tanks and trollers, you will Also be going top speed, and commenting on how easy it is. This isn't as true with ranged damage dealers. Ranged Blasters don't get many of the benefits of a Kin - the heals require an enemy within melee range, as does FS and Transference. SB is still nice, and ID is much appreciated, but that is a lot of Buffing that is lost.
A word here about people who yell for SB, and how to react to them. On the one hand, if you are on a team with a Kin, and they are pretty regularly hitting you with SB, it is totally annoying to the Kin when you yell out SB PLZ every time it runs out - it is implying that he/she is not doing their job. You will get your SB pretty regularly, so be more patient. On the other hand, there is no point in reacting to people who yell SB PLZ - SB is Awesome for them, and they want it really badly as often as possible, and instead of reacting, just keep giving it to them as often as possible. Lets face it, that is one of the reasons you are on the team. That is one of the reasons that Kins NEVER have to worry about being invited onto teams - Everyone wants Kins on their teams. I want kins on my teams. Even when I am also a Kin. And a big reason for that is because you provide SB. Tankers love the SB/FS because it solves their End probs and lets them feel like tanker level scrappers. Scrappers love the SB/FS because it lets them feel like gods. Seriously - a Spines Scrapper with Two Kins on his team? Heaven. Controllers love the SB, because they often are Kins themselves, and need all their holds more often, and like boosting their pets. Blasters kinda like kins, but less so because they don't really understand how kins healing/buffing works. But if they are Blappers - yeah - they like FS too. And the FS/Nuke combo? Yeah - they like that too. So it is kinda a trade off - on the one hand, you never have to worry about waiting to get invited to join a team. And when you are on a team, everyone loves you. On the other hand, some people are just overly annoying about Loving you on the team.
A word about Multiple Kins - Love them. Now I get SB too. Which means that FS can double up. And with Two FSs (or Four if doubled) Everyone is at the damage cap permanently. And now pretty much Everyone is always SBed, so there are fewer people complaining. No such thing as too many Kins. Well, to a point.
Fourth, or Fifth, or whatever - Use your Buffs to Debuff. This is the hidden awesomeness of Kins - most of your best buffs also debuff your enemies. Transfusion slows Regen. Siphon power sipphons power. Siphon Speed from a Boss. Use Transference to Sap your opponents. (don't sap sappers - that doesn't work). FS lowers their damage. This works nicely with Rad, because all of your powers decrease defense. Irrad Really decreases defense. I slot all of my rads with the Achilles Heel Proc to Decrease Resistance. That is a serious lot of debuffing. It is Very helpful in AV/EB/GM fights. Not quite Rad defender debuffs, but very awesome. And the Slow Regen of Transfusion is totally awesome in AV fights.
Sixth - Accuracy bonuses are the most important ones. You need to hit the enemy for most of your buffs and debuffs to count. Nothing is worse than Missing a key Transference or Transfusion. Slot for accuracy, search for accuracy IO Set Bonuses, and I took Tactics. I have accuracy IOs in almost every Kin power. Totally worth it. I also put the Celerity Stealth IO in SB - I am often stealthed as a result. Which helps.
so - to summarize:
Always Have Break Frees.
Choose offense or Defense
Always Stun Stun Stun
Don't react to annoying SB PLZers
Enhance Accuracy.