I've handled the Dodo, and had little trouble with it, but that's a _thin_ handle. I don't doubt at all that the thicker FRN D'Allara's harder to close.
I'll point out, though, that I _do_ use my thumb and index finger to operate the AXIS lock on my Griptillian, and it doesn't bother me. It just seems to work more smoothly with pressure applied to both sides of the bar.