Just a day before I tried to play as British RE vs 2 WH Expert CPUs to check complains about it in this post and that's result:
Pak 38 sometimes penetrate Churchill in front at looong distance;
Pak 40 usually penetrate in front at same distance;
AT squads with scherks penetrate Churchill in somewhere of 90%;
Panthers drive around and 100% penetrates Churchill in rear projection and have no dmg back with Churchill main gun loaded with AP rounds.
I tried to use three of them at once, loaded with HE (2) and AP (1) rounds to fight against troops and AT guns but they where really hard to get enemy AT guns that shoots from ranges 2x far from Churchills guns.
Supporting them with infantry was not so effective as u may thing coz WH have MG, LMG and Mortar teams to pwn off any infantry in their attack range.
So for me looks like Churchills are sufficiently durable but not overpowered. You still need to care about them and need to think when to use them and against what. Just like Tigers or Pershings