[rgoulter]

If you use "home row modifiers" (holding down f/d/s/a or j/k/l/; acts as Shift/Ctrl/Win/Alt), then it's less reaching for ctrl.

Although I'd also recommend making Esc available on a thumb cluster.

[Jedd]

This feels messier, partly because it's easier to fudge accidentally, but very much mostly because it relies on your configuration being propagated. I understand that may work in some shops, but generally it can't be assumed.

ctrl [ works everywhere vim is installed - no customisation required at all.