Just one caveat: the Pro overlapped in time with people running a lot of 16-bit code, and I think the Pentium MMX was faster for that, or at least that the Pro didn't offer much edge.

The pro did register renaming. But the way it worked, if you wrote to AX (16 bit write) and then read from EAX (32 bit read) it caused a pipeline stall from resyncing the registers.