I think my Heart Interface Link 2000 quit...

Look at the Magnum 2800 series. They are a pure sine wave inverter. The control unit for the Magnums use the same four wire telephone cable used by the Xantrex converter you have. The connector needs to be modified as the wires terminate differently. I believe there is an adapter available that will change the connection so you don't need to cut the wires and re-attach the plug with the proper wire oreintation.

I have the Freedom 2500 and when it dies I'm going with the Magnum MS2812 and the their remote panel. Look at the iMarine web site for best prices.