I just saw my reply came after you made your choice, but I'll leave it here for others...
NOT Mares! I've been to certification classes for both, serviced both many years, dived both. I especially dislike Mares for destroying Dacor's parts availability, but I'm not that impressed with their stuff anyway, particularly as far as value goes. I dive ScubaPro's older models now (mostly), but there are plenty of regs that have excellent performance that just don't advertise SO MUCH as Mares and ScubaPro! Consider offerings from Zeagle, Oceanic, Aqualung, Atomic, Apeks, Genesis for example. BTW, I wouldn't trust an "unbiased review" from any magazine that takes big advertising bucks from the contestants. And the size and quantities of the ads do not affect the REAL quality of the reg- it ain't necessarily great just because they say it is! My advice is to save some money on the reg- you are mostly paying for advertising. If you have to have one of the two selections, get the SP.