Couldn't confirm in rxvt-unicode, but can confirm for xfce4-terminal. My xfce4-terminal sends ^? (ASCII DEL) for backspace, and claims to be xterm, but under screen, the backspaces become ^@ (ASCII NUL). I'm not sure what is causing this, as it works fine under gnome-terminal and (for me) rxvt-unicode, both of which are also using ^?, and gnome-terminal claims to be xterm.
It may be that xfce4-terminal isn't as compatible with xterm as it claims to be.
If you are still experiencing issues with rxvt-unicode as well, what version of that package do you have installed?
Couldn't confirm in rxvt-unicode, but can confirm for xfce4-terminal. My xfce4-terminal sends ^? (ASCII DEL) for backspace, and claims to be xterm, but under screen, the backspaces become ^@ (ASCII NUL). I'm not sure what is causing this, as it works fine under gnome-terminal and (for me) rxvt-unicode, both of which are also using ^?, and gnome-terminal claims to be xterm.
It may be that xfce4-terminal isn't as compatible with xterm as it claims to be.
If you are still experiencing issues with rxvt-unicode as well, what version of that package do you have installed?