Can't comment on sizing but would recommend the fabric radial shallow or the fabric shallow race ti version. I find it comfortable. I find my butt is comfortable when I'm sitting more towards the front of the saddle at times. But I think moving your position, getting out the saddle when possible are good strategies. On a descent I will often get in a aero position and scissor the seat between the legs which can give me some relief. I mean if you ride for hours I don't think there is saddle out there that will be 100% comfortable if you sat in the same position the whole ride.