You can get replacement seat meshes for your Vision seat from Hostel Shoppe: http://www.hostelshoppe.com/cgi-bin/...ory=1006385913
IIRC, they bought the Vision designs and spare parts before coming up with the Volae recumbents.

That being said, "most comfortable" really depends on the design of the bike and the design of the butt. Larger/speedier/more laid back riders tend to like hardshell seats, I think, but then I'm a larger, speedier rider.