Wouldn't you hit ESC with your ring finger or middle finger instead? (When I used vim, I preferred Ctrl-C so I would not have to move my fingers so far.)
That would require lifting my hand off the home row, which would be uncomfortable on my wrists. Playing around with it now, the motion seems to be more of a sideswipe, with a bit of muscle tone to keep the finger from just bending out of the way.
Side note - I've noticed a big improvement in general hand pain since I got into climbing regularly, and specifically starting working with a hand exerciser.