I think it would be sensible to make all the changes together.
If you already type e.g. T with the wrong hand, then it's annoying to start typing it with the correct hand (because it's on the other side of the split), then learn a new location with a new layout.
(Do also consider Dvorak. The difference is not really worth an argument, but at least with a programmable mechanical keyboard one of the main advantages -- that Control Z/X/C/V remain in place -- can be kept with Dvorak with a small adjustment to the layout. I've never tried Colemak, but I do like the hand alternation design of Dvorak, and I think I would miss it.)
Thanks for the advice/perspective; it definitely helped me decide how to proceed.
I'll definitely make all changes at once, then. I'll experiment with both Dvorak and Colemak for the letter keys.
Shorcuts are not much of a problem for me, extensive MMO raid gaming in my teen-20's made sure of that.
I miss AutoHotKey (AHK, windows program) very much, haven't found anything to remap keyboard inputs so extensively and granularly on Linux. KDE helps a lot, but nowhere near enough for my taste. I'm very excited for the EZ Oryx firmware tool in that regard, as it may replace AHK (and whatever it can't do yet, I can probably program, which is sweet).
If you already type e.g. T with the wrong hand, then it's annoying to start typing it with the correct hand (because it's on the other side of the split), then learn a new location with a new layout.
(Do also consider Dvorak. The difference is not really worth an argument, but at least with a programmable mechanical keyboard one of the main advantages -- that Control Z/X/C/V remain in place -- can be kept with Dvorak with a small adjustment to the layout. I've never tried Colemak, but I do like the hand alternation design of Dvorak, and I think I would miss it.)