We also installed the Xantrex Prosine 1800i.
It lasted one year and quit. The error code was "contact the factory". Xantrex replaced it promptly without waiting for the old one to come back, they just asked me to remove the serial number from it before we put it in the trash.
So factory support was excellent, but I don't have much faith in it now. It was installed by an electrician recommended by Joel Potter (Lean Marine in Ft. Lauderdale), so I don't think that was the issue.