ic2 is under going a lot of updating every second day there is a new version on jenkins, atm I have left out ic2 from the packs I been making testing, even with the talent working on ic2 there seems a lot to do, as yet there is no word of anything really new, but I would settle for the core stable working mod, but that will come in time, so test other mods & replacements for this or that mod until the core mods of most ftb packs are stable, some are real fun, like nitro creepers on a hard mode server, not instant dead if in iron but almost, adds an edge to the game play.
PS: when making a pack add mods one or two at a time, makes it less trouble to track down issues.