I'm a little late to the party on this one, but the M1 was essentially just a self propelled anti tank gun and that respect no different to the vast range of SP AT guns cobbled together by the Germans, Russians, Italians and to a lesser extent, the British.
What was unusual was US Tank Destroyer doctrine, which was rather more aggressive in the use of SP AT, envisaging them actively seeking out enemy armour to destroy, rather than moving rapidly to set up nice reliable Pak fronts like the Germans, Russians and British did.
Using WW2 tech, this didn't work too well, but it works very well indeed if your SPAT weapons happen to be AT helicopters. When I'm not on my phone, I'll chip in a bit more.