I've used neg scans, try to match the print as closely as possible, and have made several Blurb books tha I find somewhat inconsistent from book to book in the quality of reproduction. That said, I'm sure you could generate some good scans from RC prints.
And yes, this is a somewhat borderline topic for APUG, so just report posts if you aren't sure. Thanks.
SuzanneR, is there another company that would offer a better product, that you know of?
I'll definitely be scanning from prints.