So is CabDriver engaged when using the main outs? I thought that was the monitor out only.
No, CabDriver is only engaged when using monitor out with the 'cab off' option ticked.
And it's mono only unfortunately.
CabDriver retains a bit of the profile's cab portion incl. the Interaction poweramp - cab, whereas you'll lose this when switching off cab in the main rig.
CabDriver is a genius feature IMO.