I've had my Domane SL5 for a couple years now, and it just plain works. What climbing we have in central Ohio is mostly sub-3 minutes and relatively sharp, and the Domane's stock gearing does good job of getting through it; I've not yet run out of gears. I find that I do not notice the Isospeed in action, but regular Saturday rides are 80-95 miles and don't leave me worn out, so I take that as sign that it's doing it's job