It's logical that it's researched from the Church I, it's based on it after all. Besides, most trees have crossovers from a heavy or med line to a TD line.
Tiger P -> Ferdi
T-34 -> SU-85
Sherman E8 -> Jackson
Anyway, I think both the Church I and the GC are terrible (i have only played the former, but just from looking at the carrier I can tell it sucks). The Church I is bad in every way except for the gun, the latter has good penetration and accuracy but the gun is otherwise mediocre, and it's mounted on a platform that has:
A huge slablike front that every tier V+ and many tier IV tanks can penetrate
Very retricted gun movement
A large roof that arty can hit relatively easily.
Oh, and you can hit the sponsons inside the tracks for HP damage through the front- that's right, you can just track it, move slightly to the side and peck it to death whilst keeping it permanently immobilised.
Edited by Platypusbill, 06 March 2013 - 06:40 PM.