On that front: I've been using wezterm which includes a built-in tmux+mosh functionality, and it works quite well. It gives you first-class scroll/copy/paste management and multi-windows, plus session re-attachment. Probably 50% of my use of my mac is just SSHing in to my Linux box, and wezterm works great for that.
Last I tried there’s 2 major limitations, one is that the version on both ends has to be compatible, another is that it seems the wezterm at the host must be available in the system default PATH. This makes it hard to adapt to arbitrary remote systems that you have limited control of. Tmux+mosh doesn’t have these limitations (well I’m sure the mosh client and server must be compatible to each other but given it is so stable that the last 2 updates are 5 years apart there won’t practically be any problems).
Yes, the versions between client and server do need to be in lock-step. As far as needing to be in the system default path, I haven't run into that: when I initially started using it, I had dropped the executable into ~/bin and that seemed to work (that is in my shell path).
It depends how the rc files are initialized though. I remember last I check I couldn’t get it work on one system (that I don’t have control over those in /etc and those set in my home is not initialized at that stage.)
Mosh implemented a flag to include in the client side: —server=… which solves this problem.
