For the '51 vs PIC debate, I see many manufacturers of the '51 series getting the guns in position. You can today - in volume - buy low pin count '51s for 50 cents or less.

1. given a chip with N bytes of RAM to start with ...
2. not needing to save the PC for up to 8 function calls in that RAM does not conserve RAM,

Let me chime in and state:
The above does not per se save RAM, it adds 8*n (I do not know how much the PIC saves) bytes to the effective RAM size. This, however is only true if the nesting is 8 deep.

Erik