The B18 is very similar to the B66/67/68. (actually, also the B72)
I think it's a gorgeous saddle, but too expensive for me. I ride B67, and love the fit and comfort. I've done 50+mile days with no butt problems at all. (Mimitabby has done much longer rides on her B67s, and has one that is 30 years old!)
If you mesh well with any of the B6x series or the B72, I'd go for it! (and if you order it from www.wallbike.com you have 6 months no-questions-asked to try it out.)