Personally, I really couldn’t handle the keymap layout at all. I tried to use it for a few hours and it just wasn’t working for me at all. I think the default keymap only really works if you don’t do the arrow layout.
Having said that, I think the keymap I settled on (linked above) is perfect for me and it is definitely my favorite 40% (45%?). I actually have two of them and most of the parts for a third!
One of them just gets handed off to locals who are interested in test driving it to see if they can handle the size change, but of the 10 or so people who have tried it, most of them bought one themselves, with one person deciding 40s weren’t for him, and one going for other, cheaper, 40s.