It's a shame the publicly available releases of MVS etc. won't exploit a multiprocessor box. It would be interesting to see what kind of performance you would get out of a new copy of z/OS running on a 16 CPU machine.
I'm not sure what a 16-CPU (core?) machine can pull off in terms of MIPS, but my 12-core Mac Pro will do about 4600 MIPS with nothing else running in the background. Sadly I've never actually bothered to benchmark the system properly. I just know that it will IPL z/OS V1r10 from a cold start in under 3 minutes (can't remember what the loadparm was for that run though, I do recall that I wasn't booting off SARES at the time and it was the full ADCD environment being brought up).
I should really get back into that stuff. I just never found any practical use for any of the knowledge. *sigh*...
Hercules is a great project though. The guys behind it are superbly nice people.