I ordered the Panzer Tracts 2-1 on the early Px IIs, and will report back what that has to tell us (when it arrives). Of course, if anyone else has it, they can report in now and save me the trouble.
I strongly suspect (as ripley stated) that early versions had full non-slip, and that later versions had only partial. The thing is, I would bet that the Ausf covered by this kit (the A, B and C) probably all had full non-slip ... because the bulk of them were built prior to full-on war, and the need to conserve materials. I would guess that after seeing combat in Poland, and after full war was declared, they may have at that time decided to save on materials. But I doubt that any of the A, B and C models that rolled off assembly lines, had only partial.
That is just me, guessing.
As I said, when I get the book, I will research what is there, and check out any photos or text on the matter, and report back.