I'd always used Ctrl-a in screen because it was the default. When I moved to tmux I just moved it there, but tmux lets me send the Ctrl-a key sequence through to those apps.

So if I want to go to the beginning of a line in Bash, I just press C-a C-a (which actually works if I hold down Ctrl and press 'a' twice.

Not a big deal at all, and since I remap Caps Lock to Ctrl, the command combo is right on my left hand. (I slide my hand over a bit as if I were playing guitar or piano, rather than stretch fingers, so pinky on CapsLock, ring finger on a.)

I've been doing the same for a while, despite the fact that C-\ is in fact sort of already "taken" by default (SIGQUIT). That's not something I use often, but when I want it it's still easy enough to get by just sending C-\ twice. The only downside is occasionally (whether by accidental double-triggering or hitting C-\ out of habit when not actually running screen) killing foreground processes by mistake.

You should, ctrl-\ is the best process killer. No way to escape from xtail without it, for instance. And sometime it will help getting out of python scripts like nosetests.

I use Ctrl-o as my key bind for tmux. Maybe Ctrl-\ is a better choice for me, since Ctrl-o conflict with something that I does not always using.

ctrl-\ here, too.

The guy introduced me to screen recommended it. His words were "if you're an emacs guy, having this mapped to ctrl-a is going to drive you crazy"

I've been using `

Isn't that siginfo?

You can send it to ping on linux to print a report line without terminating, for example.

I use ctrl-_. In many terminals you can generate it with ctrl + 7 and/or ctrl + ?.