I like the Churchill, but it is slow. Very slow at 15mph (max!).
The 6 pdr or 75mm main gun (if HTC adds it, having both options would be smart, imo), are limited. The 75mm would be good just as the M4A3/75mm is good, but AP would be better only than the T34/76. The 6 pdr would be better at AP, but HE on par with the 76mm M1A1 cannon (weakest main gun HE in AH).
This thing would be a slow moving target. It would have value in scenarios, that is it.
Now, ask for the Cromwell or the Valentine and you will get some support (at least from me
).