Not a fan of moving to 1.7.x for a large variety of reasons. 1.7.x, for me, has been nothing but buggy, laggy, and really just not good. The changes to mods from 1.6.4-1.7.x have been, IMO, unfavorable, and there are still some good mods that are either still in beta or haven't been started at all yet (for instance, unless something has changed in the last couple of days, TE's mod coder has separated the piping, liquiducts, itemducts, and conduits, from the main mod, and hasn't even put out a beta for it yet).
IMO, 1.7 was a very insignificant update. It didn't really do a lot for the player and I just don't feel there are many good reasons to upgrade...ever. That being said, I am not a coder, and there were a lot of coding changes. Maybe those were positive things, I don't know. But yeah, from a player perspective, I just don't see the appeal of moving to 1.7.x.