[_TwoFinger]

Here is my current keyd configuration (on US QWERTY hardware): https://dpaste.org/aGp3o/slim (I'm not entirely happy with it, though.)

The one thing I wanted the most was to avoid any long presses. Everything that requires holding a modifier, even if I do it touch-typing style, with the opposite hand, is unpleasant (to me). So, besides moving most of the punctuation characters to lowercase positions, I also switched to sticky modifiers. (keyd might have some flaws wrt sticky modifiers, and they... get stuck. Not when I want them to be. I might try to go back to XKB.)

Regarding the home-row modifiers, I've only tried moving Control there. I always ended up triggering it by mistake when typing, because when you are typing fast, there is an almost unavoidable overlap in certain sequences, you press the next key before fully releasing the previous key. Some people advice practicing, other software provides various options with timeouts, it's a rabbit hole of work-arounds. So I settled with sticky modifiers.