My experience with a Prosine 1800 (and 24v model, too) was that it was unable to start a refrigerator motor. Even with enormous DC cables and over-sized AC lines to the fridge, too, it just couldn't kick it over.
This is second-hand experience. I never determined if the problem was the battery being too small or the inverter lacking guts. My overall impression with the Xantrex inverters is very positive.
Running water is one of those things we come to rely upon VERY easily once it becomes available.
I also think you should determine if the Prosines are designed as "mobile power" or "fixed" in terms of their grounding provisions. Depending on how much you want to do with your cabin in the future, you could find yourself taking out the Prosine(s) soon after getting them in just to install another inverter that can properly be connected to a breaker panel etc.