4.0 and 5.1 is almost nothing. Still 1.1 less speed is irrelevant if you can eat 9 shots (KV1 - 7).
Sherman also has smoke even tho USF have mobile mortar so...
30 armor is nothing. It translates into 79% or 70% chances to penetrate vs Pak40.
Anvil locks you out of Comet. KV1 locks you out of T34/85, ISU, IS2, KV2, KV8...
• 21% speed isn't nothing.
• 9% lower chance to hit from Pak40 isn't much, but that armor is more efficient against Panzer 4.
• Smoke is trash, it slows the unit and the smoke itself isn't even as big as USF canisters, the churchill takes some time to crawl into the smoke backwards. Churchill is a big and slow tank, it gets even slower in smoke and many players already know about attack ground option. You are better off not using smoke while retreating.
• Grenade is good.
• 40% Churchill HP isn't the gamechanger.
• 80MP/15 Fuel isn't that much of the cost difference, but it still something to consider.
• Churchill gets the extra repair ability where KV-1 gets the bonus +20% reload speed on Churchill.
You can buff KV-1 to the performance/price of Churchill, but both units are still going to struggle to find the place in the game. One Stug or Pak with faust squad is all you need to prevent the KV1/Churchill advance.
Perhaps there is a use-case scenario for 1vs1/2vs2 games where these tanks can be efficient at disrupting enemies, but 4vs4 it is a veterancy pinata with no firepower against Panther and up.