I run my S40 with 42's running tubeless at 40lbs. It's my cushy, squishy, go anywhere commuter--but is also what I would ride with friends. It's a lot of fun to ride, and even with those fat tires, it's no hog. I do suffer some recumbutt with it though. I run my V20 with 25's running tubeless at 65lbs. This bike waits for no one, so it's what I ride when solo; the miles fly by, fighter jet style. It's also the more comfortable of the two. No recumbutt and better support distribution for my 5'4" bod. When climbing, the V20 has noticeably less wheel slip than the S40, but you can put more leg into the pedal stroke with the S40's more upright seat angle. If, for some reason, I had to get rid of one, that would be a no-brainer for me: the V20 stays.
