1.6.4 for FTB will be out soon, tweets from yesterday and today indicate the packs themselves are pretty much ready, just waiting on the launcher to update, which they also said would be released as a beta soon as well. 1.6.4 for RR is also very close to hitting a stable release, so at this point it's which pack has the more interesting mod selection, but since we have no idea what FTB's will include it's up in the air for me. Personally, I love getting to play with the new toys in mod updates, as well as all the lovely bug fixes so restarting the world every once in a while doesn't bug me in the least.
Also interested in which mods you removed to help reduce lag in RR. But anyways, long story short, RR sounds great to me but I am also willing to wait a bit for FTB's 1.6.4 pack if that's what the majority want.
One last note, for those that are worried about a world reset, if we move to 1.6.4 that should be the last one for a long time, 1.7 mods are going to take a LONG time to update.