I haven't tried the speedmaster but have a CP-31 and 51. Both are nicely compact. I think it depends on the space you have available. The -51 is already pretty big. I bet the speedmaster must be huge.
Also, 32" wide implies pretty big paper, there's no cut-sheet that was ever made in that size I think, at least not from Kodak. (Maybe there was but it was probably rare). I have some 24x30 cut sheet endura but haven't seen it larger than that. SO, that implies roll paper, which is it's own hassle.
I can see wanting to do optical enlargements though, as they are going to be inherently better than scan-and-lightjet methods I think, for the most part. (all else being equal which it never is... ;-)
frotog, where are you at and how much do you want for your cp-51? ;-)
As for contrast masking for RA-4. I have looked into it but not done it. It doesn't seem like it would be that bad. Probably could be done without a pin registration system, even, given they are going to be softer, unsharp masks anyway... Ctien had some good info on that in his (free) book available on his site. Barry Thornton had some good masking info in one of his books too (albeit related to B&W). Does anyone still make those temporary masking systems, they were like a short-term contrast mask that you could re-expose and re-use. Not sure what technology those used... but it was pretty cool.