I have images in both the RM and RF side of SPK. They haven't done a lot of advertising at this point because they were having problems making the site stable.
At this point they want to have everything working without glitches on the buyers (and uploaders) sides - they've hired a new tech and a new customer service person, so hopefully things will begin to improve there.
I like the idea of prints too - I hope they get to that because it be somewhat advantageous.
I like to support start up sites too - have you tried
Feature Pics yet? I joined there in February and have just reached payout

A little different business model, but I like that I can set my own prices for images, and that you can select RM or RF as well as editorial for licensing. They also have an FTP or multiple image upload.