[hobobaggins]

I'd switch to Userify if you have a team to distribute keys for, because it's ultra-lightweight and also keeps you from messing up permissions on the ssh key/directory, which I've done too many times! (also it does sudo which is quite nice)

Also, restarting ssh will not boot you out of the session (your session has already been forked as a different process), so leave your terminal window open (to fix any screwups) and then log in on a separate window on the new port and just make sure you can get in.

For backups, don't set up logins from your main server(s) to your backup server; log in from your backup server to your main server. That way, if someone breaks into your main server, they can't get into your backup server.