They're OP on a few levels... its a lot better now.
If you want examples of why its overpowered then i'd have to say its because of the sustainability of it. Saying "if you set it up wrong and light on fire and die 5 seconds later"... Lets be honest, if you're too retarded to see the molten bar filling up as you try it out then you deserve to die. The kenetic generator needs to be tweaked so it doesn't do that. Right now it is just all over the place. The pack has come a LONG way, so to anyone thats keeping up to date with the versions Vs using the released FTB pack versions i can see why someone might say its way OP vs other people like Lambert who doesnt know wtf you're talking about.
I know in the first FTB Ultimate you could make the suits fully decked out probably 20-30 min into the game if you were going especially for that... whereas now with the changes to the "wiring" it takes a lot more time and farming to get it all in there... plus needing the tesseract cases and energy cube cases is a nice addition and balance.... I don't think any of the Ultimate versions have that requirement yet? maybe 1.1.2 as i havnt played it.
The power suits i suppose are balanced if you do not have something like EE3 in your package making access to Ender Pearls retardo easy... Endermen hit like trucks and are not something easilly farmable early game.
OP now?... they're starting to drift off, i feel that they might be a little bit OP but not enough to warrant discussion anyways, especially with how much this mod keeps changing on a weekly basis.
TL;DR - You're playing an old version of the mod if you think its still OP.