I built the multi-chined Sea Rider. I thought it was a pretty good hull, but couldn't test it thoroughly because I hated the fit of that style (short cockpit, low deck). I was surprised to see a post by Tom Yost here, last month, where he didn't see any advantage to building the mc version:

http://www.kayakforum.com/cgi-bin/Building/index.cgi/page/1/md/read/id/205437/sbj/skin-on-frame-sea-rider-single-chine-vs-mult/

I had been looking for another multi-chined boat to build, and found this one, which I'll soon begin:

http://www.paddlinglight.com/articles/free-kayak-and-canoe-plans/siskiwit-bay-multi-chined-kayak-plans-for-plywood-building/