I am interested to hear how your modified Vitesse works for you, Andrea!

For me, I think I just needed to stick with it for a few more rides. I've had two rides since I posted and no further problems. It also seems to depend partly on my shorts. The Shebeest SSS in small gave me trouble, the same shorts in medium caused no trouble at all (although they are a bit too big in the legs). I have one pair of Pearl Izumis that are fine, another with a different chamois that are awful. So I think I can stick with the Vitesse.

I am glad, because I bought a second one for my new Soma. I am going to try to ride a Brooks on that bike, and then the extra Vitesse will go on my mountain bike. (I currently ride a Selle Royal Viper on that one, which is shaped somewhat like the Vitesse but is too squishy. Otherwise it's a rather nice saddle.)