To clarify window management that I'm doing...
Gnome 3/Gnome Fallback/Classic(No Effects) are automatically assigned to "metacity"
Gnome Fallback/Classic is automatically assigned to "compiz"
XFCE4 is automatically assigned to "xfwm"
To change XFCE4 I am changing the configuration in
/etc/xdg/xfce4/xfconf/xfce-perchannel-xml/xfce4-session.xml
from "xfwm4" to "compiz" as you can see on line 12.
You can also always add the compiz --replace command to startup but you are kind of asking for trouble since at startup you are telling your desktop to load one and then the other. Not ideal. It's really more for...oops, or..it broke.
All right..Gnome 3 still works, Gnome Classic works, XFCE works, on to LXDE....