Comet is not near perfect....
1.for competitive play, the advantages of Anvil tactic is overpowering the hammer one, if you Chose comet, you lose churchill to suck the damage of the late game german uber panzers, Comet is squishy as hell and comes late, and its price is very expensive and still hopelessly lose to a panther.
2.And you lose heavy engineer option for chosing hammer tactics, that's the only effective infantry the UKF can get, IS is a MP black hole,and their combat perfomance is very situational which relys heavily on cover, AKA, none practical since there won't be covers avilable whenever you need it.
3.Again, Churchill, this tank is the only hope to tank those Uber Jadgtiger/Elephants, I don't find that many axis player whine when the Axis W/R is 80% not long before in teamed game.
Must be why Aimstrong usually uses Hammer in these tourny games huh.
IS are a MP black hole, but theyre still lethal as hell. (as are commando's).
On a serious note, The Churchill is OP. But the Comet is still a good tank, very good at countering medium armor + panthers. (and its armor is not crappy at all...).