From my experience:

1. I typed around 60 WPM before on a standard keyboard, now it’s barely 25. It may be because I don’t use standard keyboards at all anymore though.
2. I learnt colemak with my first split keyboard since it seemed like if I was going to learn a new layout, then I should commit to it entirely. I think keeping AZERTY (since I’m french baguette haha) would have just made me even slower on standard keyboards because there wouldn’t be much difference with my normal workflow. Separating the two layouts entirely seems better to me, but you might also say keping the same layout to some extent is better.
3. I went from a full-size keyboard to my monkeyboard, gradually removed keys (left row, top row, inner thumb keys) and now I’m at 34 keys with my triboard. But making the jump could also have worked seems it’s a complete change anyway.

Yup. gives nickel back

Sorry, I forgot to convert my orgmode formatting to markdown. Fixed it

I’m not a distrohopper, but GNU stow is delightfully simple. See my dotfiles as an example.