I use neo and find QWERTZ annoying to type on other people's computers. I still use it on my phone though, that's a completely different kind of typing and feels completely separate. Ergonomic layouts also likely wouldn't work well with swipe typing, half the words would be dashing left and right on the home row ;)

Other people's computers are easy if they run Linux (setxkbmap de neo) and okay if they run Windows (there's a no-install no-admin tool to remap), but you can't switch a Mac temporarily without installing the keyboard layout and even then getting the layers to work is awful. So I'd say you're half-right about that.

I have no issue with the shortcuts, it takes a while to learn them anew but they're no less convenient because of it. I started using Emacs years after Neo and I have no complaints about the keymappings, so it really can't be that bad ;)

In my experience, still having azerty on the phone is not too inconvenient: while I type blind on the Bépo, I stay visual with Azerty. This is enough of a difference that I don't confuse the two.