I like the 75 version better as far as looks, and I don't need a rail, so that was my choice. I am sure either is great since they are inherently the same machine. I think this is mainly an issue of aesthetics and perhaps, availability.
Newer 75s seem to have the upswept beaver tail, so I think that difference is moot.
Now, I am lusting after a PCR (I've made the convincing argument that we "need" a smaller companion
).
But, I think my message is clear:
If you decide upon an SP-01, then you NEED a P-01; and,
if you decide upon a 75, then it is obvious you NEED a PCR, too.
Replicate the patterns across scales in this fractal first world...