Hmmm... I like the idea of having available a halftrack w/ a 75mm cannon mounted. I suggested the Sdkfz 251/9 numerous times in various threads. It would give LVT4-type support for taking down towns and other OBJ.
This version with the PAK-40 installed would give it tank killing ability for sure, but how would it serve as an OBJ killer? Meaning, yeah we all know the PAK-40 has a good HE shell, but would it offer the same rate of fire and HE ability as the Sdkfz 251/9 and the designated infantry support gun? If the 251/PAK-40 were put into the game with hope of it being an equal to other tanks... it offers nothing the Pzr cant already due with far more armor protection.
I'll for sure vouch for the 251/9, but I'll put on hold my endorsement of the PAK-40 version for now.