I am suprised noone has asked yet, but it seems one (if not THE) argument against a FTB pack with GT seems to be that "several"/"a large portion of" modders won't give tech support (i assume that means something like "if there are problems/incompatibilitys in a pack with GT, they will not get fixed, even if GT is not involved", everything else would not make much sense).
So may I ask which modders/mods are affected of that, and why that mods are so essential for a pack that you can not just exclude them from a GT pack?
The only mods that GT really depends on are IC2, NEI(to a certain extend), Forge and FML. Greg is part of the IC2 so that should not be a problem and i do not see ChickenBones and the Forge/FML participating in any boycotts.
Mods i guess would fall out are TiCon, Natura, Computercraft and MiscPeriperals (listing them because at least one of the devs has "expressed displeasal" with GT) are not what i would call essential, especially not for a GT pack.