Ladies and gentlemen, we have a match! No pad holder adjustment needed when switching from the Zipp tubulares to the Bont carbon clinchers, nor any shifter indexing adjustment. Woohoo... all I need to adjust is the barrel adjuster on the brakes, as the clinchers are narrower than the tubulars. The wheels ride great, too. I'm a happy camper. In case it's helpful to the OP, my wheel experiences thus far:

Torelli Bormio alloy clinchers: They've been solid, provide a smooth ride, and I rode them as I went from 225# to 193#.
Bontrager "Race" alloy clinchers: catastrophic failures.
Zipp 404 Firecrest tubulars: Fast, handle well, and you feel every irregularity in the road, especially if you pump them up to 130psi for minimal resistance.
Bontrager Race XXX Lites (the pornstar wheels): So far, so good. Very light, with a ride in between the Zipps and the Torellis.