My healing wont be a factor in enrage timers. All i do is keep people up.
First off, any healer worth their salt is going to throw in at least 1-2 attacks when they've got nothing better to do so it's not like you should *only* be keeping people up. It behooves you to actually throw out the occasional attack, especially as an Operative where you get easy access to excellent damage via Orbital Bombardment.
Secondly, unless your other healer is making up for your lesser healing capabilities, it's entirely possible that a DPS or tank could die when they otherwise wouldn't had you been in PvE gear and, as such, end up reducing raid wide DPS to such an extent that you hit said enrage timer.
While I might be willing to risk 1 highly skilled player in optimized PvP gear, I would be reluctant to do more than that. If we were planning on doing more than just the first 3 bosses (Kephess is a definite healer gear check considering all of the F/T damage), I would probably just outright say "no". Honestly, if it were a pug, I would probably say no for anything other than storymode for EC or TfB, especially if they don't know the content.