I am in my third year with my B17 on my Salsa Casseroll. It is still pretty hard but generally very comfortable, as in not noticeable even after hours of riding. I usually ride with cycling shorts.
Based on positive reviews, I did briefly try the new Cambium and found it did not suit me. Rode it for about a month and found that my butt started to notice after an hour, really started to hurt after two hours. Live and learn. I went back to the B17 and now my son is riding the Cambium.