i dunno. it was never the shifters (nor the brakes!) that got my butt kicked. it was usually the legs. I raced on cyclone, then superbe, then super record, and then dura ace. I didn't ever see any real disadvantage until the brifters came along. Crits or rolling courses would get me smoked, until I finally caved and started shifting from the hoods.

Same, really, with mountain bikes, btw. Thumbies worked just fine, unless you were in a crit. Then the constant tempo changing of the bunch would wear my thumbs out. I caved here too and went for some trigger shifters.