Originally we had a ZWC 1300 and early Multiplus, all worked no problems except for a short period when I had switched Inverter to power saving mode. Inverter failed at 5 years and was replaced with later model with digital control. Still worked fine but washer failed at 8 years old (drum bearing which seems to be the weak point in these machines)
Replaced with new ZWC 1301. Would not work from day one. At each change of program it would stop and the drum would just twitch. Tried resistive loads, 3 X 100 watt halogen lamps. Didn't really make much difference but if you switched to Rinse it would Rinse but not spin, if you selected spin then it would spin. But not always. Did try with a 1000w fan heater and seemed ok ish but the isolator switch didn't like the continuous load.
That machine failed just before it's 5th birthday (drum bearing again) and under the terms of our extended warranty John Lewis refunded the full purchase price. We bought another ZWC1301 and that one worked perfectly until we sold the boat 2 years later.
Now have a widebeam with full size Ebac washer and Victron Multiplus which works fine.