The Model M is a bit stiff for my tastes lately. The Unicomp boards are lower quality than a good Model M, but they seem to be less stiff to my fingers - my Model M is higher quality, and feels more solid, but I'd rather type on my EnduraPro 104.
MX blues wouldn't be a bad choice, either. The Scorpius M10 is scraping the bottom of the barrel for quality, true, but RMA until you get a good one, and for $50, once you DO get a good one, you've got a fairly good keyboard. Or, if there's still cheap G80-3000LSCRCs available, do that, they were $65 a while back, IIRC.
I do notice that I sometimes miss keystrokes on my M10, though. (As in, the switch clicks, but nothing's sent.)