If you have like 97% def in PvE you will have 14% in PvP; if you have 24% def in PvE you will have 13% which is practically nothing. These numbers are because of diminishing returns. So don't concentrate on def for any squishie. Concentrate on +hp, res, acc, dmg, recharge, etc.
A bubbler is hard to play effectively; its not your FoTM psi/em, mind/fire, spines/regen, etc. where you spam attacks at a called target or spam taunt and webnades. FFers are very situational but can still be very effective on teams. Here's some of the strategies used by FFers: 1. high knock back slotted force bolt to KB the called target for your team to spike and kill. 2. Trap/push around a called target with force bubble for that extra 2 sec so your team can get a few more spike attacks off. 3. unhide stalkers with force bubble for team spikes and make it hard for them to AS or Shark. 4. stay in PFF when and try to get the other team to spike you even more while your healer keeps you alive. and etc.
If you are what you say you are, i'd recommend a rad/sonic or psi rather than a kinda hard to play toon like an FFer. PFF will not always save you especially when you have 3-6 players shooting you all with 45% chance to hit you in PvP. So At least till you get the mechanics of PvP id recommend a rad or even emp.
Perfect answer to my Question Neeto! That is the exact info I wanted!
I Have a FF/Sonic that i solo PVP with. Best PvP toon i have at this moment. 400 rep, SOLO mostly in Sirens. Force Bubble is WAY more powerful then even imagined.
Pros
1) Unhides stalkers - just pop Force bubble up, run around and find all the stalkers. 
2) Keeps Most melee toons off you. with exception of WP And Electric. which i don't run into that much. wp a little more but not a problem.
3) It's kill MM easy button. first PFF and force bubble up. jump next to mm, drop your pff and ur force bubble sends the henchmen flying away from mm leaving him without BG mode and alone to kill.
Cons
4) DOms Doms Doms, they drop your forcebubble quite easy and take away your best defences.
With sonic -res you can take out brutes, stalkers, corrs and mm's fast. I always have problems with Doms though.
The Defense works nice in pve, but crap in pvp. I don't even use dispersion bubble in PvP, PFF will give you just enough to jump away and click aid self when you land.
you should use dispersion bubble. If you don't, there is no reason to roll a FF for any solo PvP.
I'm very new to pvp, but from what I've read in a few posts it seems I would be better off picking a different primary other than force fields.
I'm not hung up on any particular defender set, but I wish to keep my face planting to a minimal.
I've been looking at FF/Sonic, but would absolutely love some honest feedback about the set, defense calculations, and survivability.
To make the question more clear, should I max my defense or say, focus on recharge over adding that extra 15% defense from expensive set IOs?
or should I just throw away the force field set in favor of a controller or another defender primary?
This will be for arena and general pvp.