This makes the M3 a gamble against Wehrmacht compared to the sturdier m8.
Idd it is when rushed into their lines. But the gamble is relatively low cost aswell.
About the Pak: it's the same story as with rushing an M8 into the enemy: Try to search out the green cover point where it is. And then flank it or force it out with arty, or get a second halftrack and use that one as bait ... etc.
I have had succes doing this in the past even vs the likes of Aljaz.
I still pick an MP40 upgrade on my volks over an LMG on my Grens any day.