Ahhh gotcha...and this thread is for "British Tank" is it not Iron??? Last time I checked, the Comet was in fact, a BRITISH TANK. 
Do you prefer your deck of cards in blue or red? You know, regardless of the color you chose the one eyed jack is still a ... ... ...
My point was that the Comet and the Firefly offer much the same thing in terms of firepower, speed, and armor. If HTC is going to add in a British tank, I bet they would fill a gap somewhere first. The Cromwell would at least offer some more speed @ 33mph than the M4/75's 26mph. If HTC played their cards right, they could allow 3 differnent versions on 1 chassis: the Mk I w/ the 6pdr (57mm), the Mk V w/ the M4-75mm gun, and the Mk VI w/ the 95mm howitzer.
The 6 pdr would offer better AP performance than the 75mm, it'd be nice to see some of the specialty 6 pdr rounds be added.