Speak for yourself. I prefer SHIFT, I have too much muscle memory with CTRL+ZXCV and just pushing down CTRL down with an edge of my palm.

Is that how you do it? I have always used my left pinky. As I try it, unless I'm moving my hands off home row, both Ctrls feel just too far to be confident I'm hitting the right one (and not hitting the modifiers second in from the edges, and not hitting both). Maybe it's just my small hands!

In terms of ergonomics, the curled-left-thumb "Command" activation (it's where Alt is on a normal keyboard) is my favorite thing about the Mac key layout.