I’m thinking of switching my thumb keys (currently space and enter and two of them go to a symbols layer) to shift. I find that shift makes me anxious when typing because i have to partially leave the home row, and as a result my pinky placement when typing is bad, my ring finger tends to take over and my pinky has become a mod presser and not a typing finger.
I have tried to overload the home row keys as modifiers but that is a huge mistake as it causes misfires or takes TOO LONG to aviate, there is no middle ground with that one.
I primarily use one thumb key for shift. Unlike pinkie-shift, I can comfortable use the same thumb key for characters typed on either hand.
My layout: https://mark.stosberg.com/markstos-corne-3x5-1-keyboard-layout/