Yes, another major problem is that lots of apps just ignore termcap/terminfo these days and just blab xterm-256color directly to the terminal. I've heard people

Yes, another major problem is that lots of apps just ignore termcap/terminfo these days and just blab xterm-256color directly to the terminal. I've heard people say that running it through tmux fixes that (tmux seems to be smart that way) but I have yet to try it. My 520 is currently in a box. I didn't have those issues you mention but I run FreeBSD where serial and getty is still a first-class citizen. Though I don't blame Apple for deprecating it.