Well, it probably comes down a lot to playstyle...
Siphon Speed and Inertial reduction can serve you quite happily as a travel power, but they do have their drawbacks. You need a mob to siphon speed off - and in some zones this might mean you have to siphon of enemies that are higher lvl than you and could end up with a faceplant or two 
Inertial reduction requires you to activate it, and I know some people don't like having to click a power in order to travel as occasionally it might see you falling out of the air on to a dangerous mob below...
I've got three kinetics toons. My defender has superspeed and hover as well as siphon and inertial reduction. I was taking haste anyway so superspeed was an easy pick and I took hover to give some knockback protection (and I dint want to go down the route of picking three powers from leaping).
My kinetics controller on the other hand lvled from 1-27 with fly which I then respecced out and kind of replaced with inertial reduction (admittedly I had to get to 28 before I picked it though). After this point she had no other travel power other than Siphon Speed (on auto) and Inertial Reduction. This worked very well for me and I never really had any problems getting around, the fact that it was unsupressed after attacking was an added bonus. I didn't even bother with knockback protection...
Coolio..will see how i get on...Never had SS on a char before...interested to see what its like as Ive always had the other three!
I'd suggest you go with a travel power now, and consider respeccing it out later.
Yep as a Kin secondary I'd go for both a travel power and Stamina and consider speccing them out at 28 and 35 respectively.
Getting to 28 with just Siphon Speed is annoying.
Personally I use siphon power and flight instead of getting inertial reduction. Flight works way better with the speed boost, and being able to fly is the one thing /kin can't do for you.
But that's just me. ^^;
I got all the way to 50 with just flight and Siphon speed and was fine... But at 50 I respecced out of fly (kept hover) and got combat jumping, SJ and acrobatics with inertial reduction, and I loved it!
The lack of suppression is absolutely woderful, and when I'm exemped down if I'm travelling through a higher area I always have SJ to fall back on, to prevent any mishaps with activating IR.
Plus, the difference acrobatics makes (when you spend as much time in melee is I do) feels huge. It took way more power picks than just hover and fly but it was worth it for my play style.
But as a 'troller, I'd agree with everyone else and get a travel power normally at 14 and respec into IR later if you want. I seriously pity anyone who tries to get from 1- 28 without an independent travel power... 
I've lvl-ed my /kin without taking a travelpower. Make sure to slot Siphon Speed with accuracy and you can draw it of higher lvl foes and rarely miss against lower or even lvl foes.
Inertial reduction always comes back before it's worn off with just one recharge reduction. If you activate a new application at the top of a jump the animation will be finished before you hit the ground and you'll be non-stop jumping.
I have a Grav/kin controller , i've got Siphon speed, im gonna get super jump and im NOT gonna get inertial reduction. Why? simple. Siphon speed is good but its not enough to be considered a real traverl power... you must attack foes, and thats sucks if you are in a high lvl area..
SJ = inertial reduction yeah, but Kin doesnt give any res or def powers, so im gonna get SJ to get CJ(imm res) and Acrobatics too(hold res), obsiously i'll skip inertial reduction cause i think its a stupid powers... nobody cares if you can make them able to jump..everybody get a travel power, nobody will never need you to cast inertial on them...
Siphon speed is better than SS cause it gives you a nice hasten effect, so go for it
Inertial is the same of SJ, but it DOESNT gives you access to any def/res power... so i prefer to skip it, and take leaping pool
Inertial reduction is not the same as SJ, it costs less endurance in the end AND isn't suppressed. Giving out people SJ is much appreciated because it's mostly a faster travel way.
SJ also cost one extra power. If you plan on taking CJ or the other one I'd say SJ is better. If you don't plan on taking CJ you can take inertial reduction and have another power-choice.
Fire/Kin and I used SS + SJ. I keep SiphonSpd on auto most of the time during missions.
Like I always say, siphon speed is okay, as long as you have a target. IR is cool too, had it for a while but decided I needed the KB protection that acrobatics gives you so respeced it out. It really depends on whether you have the patience to wait to L28 for a movement power. As for fitness....if you have the patience to wait till L35 for transference, then endurance won't be a problem after that...Enjoy 
The Good:
Krazy Mary L50 Kinetic defender
Uniqua L31 PeaceBringer
Black Annis L24 Warshade
Krystal L18 Ice Blaster
The Bad:
Frenzi L34 SS/Inv Brute
I have tried many things with my kinetic toons and when there is one thing I have learned it is this: Anything except Teleport goes and benefits from kinetic powers.
You may go without any real Travelpower at all without ever looking back once you gained Inertia Reduction. On the other hand Superspeed is easy to pick up since you need Hasten anyway for top performance. Flight would be ok, too, since you just want to have multiple syphon speeded Super-Hover (supressionless, without flight´s braking problems and fast as hell, best combat manoeuverability in the game). And even Superjump is a viable choice for the mez protection in that pool if you like playing solo. (Well, I don´t too much, but that´s a different story...)
If it has eyes, you can blind it, if it has blood, you can make it bleed, if it has a mouth, you can make it scream.
My ill/kin has Siphon Speed, IR and Hover, which is quite perfect. Before IR it was a bit painful sometimes, when SS missed I was reduced to 3-slotted Hover for travel.
My mind/kin so far has gone without a proper travel power and it is very painful at times.
Especially when I end up traveling through zones populated by purples...
And even more frustrating when you miss with that Siphon.
On my Fire/Kin Corruptor I tried TP, IR, and Fly. I have to say, Fly is definetley my favourite so far.
Although IR is good if you're pushed for power spaces, I just don't like the sensitivity of it: It's more like CJ than SJ, and I just found it too hard to control.
With TP, I thought it was a waste of Siphon Speed, so I decided to do a Test-Spec into Fly.
With Siphon, you reach Fly's cap. I love it! Fly is the safest, and easiest way to travel, even if it is arguably the slowest. Another reason fly owns, is Hover as the follow up power. Although I normally hate it, it helps a lot to supress 3 siphon speeds in a mission
Fly, not so good in PvP zones 
Too many -Fly these days for my liking. As for IR its just as good as SJ. Flash has it on him and its great for him.
Im sure this may have been answered elsewhere, but Ive rolled a Mind/Kin 'troller and wondered with Siphon Speed and Inertial Reduc, is it worth having a travel power...Im thinking Sj anyway with Acrobatics or Super Speed after i take hasten....
Thoughts?