I use a tiling window manager, emacs+evil-mode, and firefox+vimperator with a keyboard.io atreus (44 keys ergonomic) and it's basically fine if you go "all in"? sometimes I have to struggle to find the layer with the F-keys spread out like a numpad on my right hand, but I don't really use them and have their features bound to shortcuts that are easier to find, and that's probably most of the reason.

I don't have to take my hands off the keyboard to do stuff like navigate text simply, pause/mute music (instead my pinky goes to the bottom of the keyboard and all the keys on the other hand change function), my software can all be driven from the "common" keybindings and modifiers like ctrl/alt/win are on my thumbs instead of being offset below my pinkies.

Importantly, i can throw it in my bag with my laptop and use it when i am traveling so there is very little context-switching that has to occur.

None of this really carries over when I boot in to windows, though, and I keep a ten-keyless keyboard around for playing video games.

I've had my eye on a few 40% builds as of late, so I'll throw another option into your list here: portability. I'm looking for a keyboard that I can throw in my laptop bag that isn't miserable to type on. I had a Microsoft Designer Keyboard for a while but it's worse than my laptop keyboard, so I'm back to the drawing board, and this seems like where I'm landing.

Ah, I've got a 100% G915 and it fits in my backpack fine for a trip to the office or something.

Maybe if the bag was filled for plane travel that'd be a problem.

I made a split keyboard for me (I need to write up that post at some point), and I just made holding out the tilde convert the right half (yuihjknm,) to a numpad. It works great, since I don't use any other keys while using the numpad, and I get to save all that space and switches for something I rarely use.

Having done both, "the mouse goes on the left" is a far easier change to make than learning a minimised keyboard layout.

So my mouse is _very_ right handed. I have some smaller symmetrical mice that are less comfortable. I'm curious how this change worked for you - Did you get a leftie mouse? Did you swap the buttons?

Symmetrical mouse, no button swaps. I'm currently using one of these: https://www.amazon.co.uk/gp/product/B073WGB8G6 but I first started doing it with a cheapy Microsoft wired mouse.