Not sure about proposed penetration - I am okay with creating a no-go zone for the m20, the m5, or the Bren carrier. Stuart, AEC and t70 should still be able to take it out.
Edit: To clarify, I think the aforementioned vehicles should be able to just barely take it out in a purely 1v1 scenario. If the AAHT is supported in any way (Sturm Schreck, Volks faust) it should win.
the OKW aaht already create a no go zone for the allied really light vehicle. the current 20 penetration on the AAHT is more than enough to pen the m20,m5, or the bren carrier.
the OKW AAHT have very limited mobility and extremely vulnerable on the move. It's an easy target for the allied anti-tank gun. If the USF has the stuart he has access to the 57mm. The USF AAHT and okw AAHT should zone each other out. UKF have easy access to 6 pounder.
If sov have the t70 he can build the su-76.