A nice to have, but not completely exceptional advantage. The IS-1 has a more than comfortable reverse speed.
It’s tied for second fastest out of four tanks. In other words, it’s tied for the second slowest 5.7 heavy. Whew, what an advantage.
It really, really doesn’t, at least not in comparison to other 5.7 heavies. The Tiger’s got the black hole driver’s port and machine gun port, while the IS-1 has the UFP and turret of many angles, which will both easily eat shells that should pen. Meanwhile, the Jumbo’s bipolar machine gun port that will sometimes eat all the spall of rounds that make it through.
Meanwhile, the T1E1 has some rounding on the turret corners, and a few perpendicular plates on the UFP around the machine gun port. If you’re aiming even remotely appropriately, neither of those will factor in.
That’s a funny way of trying to spin “Cannot overpressure like the Tiger I can”.
The high pen on the M82 shot is the principle advantage of the T1E1, however, due to a funny quirk, that extra pen doesn’t actually help all that much. There’s basically no common targets that M82 will go through that the 85mm or 88mm cannot. Armor takes quite a considerable jump in effective thickness around that BR, meaning 185mm just isn’t all that impressive. You can’t engage a Tiger II frontally, nor UFP a Panther, nor a T-44, nor a Centurion, etc etc. Pretty much the only thing it helps with is engaging Su-85M/100/French Jumbos at longer ranges.
The Russian 85mm has it effectively matched.
It is literally 0.1 seconds slower than every other 5.7 heavy reload, barring the Jumbo. It also has a ready rack of only 4 rounds, after which it reloads much slower (13 seconds on my non-aced crew).
By 2. Nice to have, and arguably one of the only consistently useful advantages it does have, but no way enough to offset the armor deficits.
A comfortable advantage, but not a game winning one.
32mm of pen with 38g of explosive mass is “good for light tanks”? For reference, the .50s will pen 31mm. Anything you can kill with the 37mm, you could more quickly kill by just spraying down with the .50s, usually from behind complete cover, and without having to alter your aim to the different ballistics of the 37mm.
Barrelling people with .50s? That’s not been a thing in quite a long time. You can indeed track people with the hull mounted .50s, but that requires sitting out in the open, exposing your weak hull armor, meaning it’s only useful against already crippled tanks that are completely unsupported. Nice to have, not a reason it should be comparable to the Tiger E.
Because, if the KV-220 is properly angled and with it’s turret facing the T1E1, it can only be penned through the mantlet (only destroying the gun), or in a small and easy to wiggle cupola. Meanwhile, this is what the KV-220 sees:
