Before we get too far off the track, one of the major reasons that I was attracted to the little Yamaha 1000, or the Honda of the same size, is that it is physically small and light weight. 28 lbs !
Now, for that size and weight, you can do a lot of things, if not run your a/c. On a larger boat, it would afford you a completely independant charging system-to charge say your starting battery if needed. Given the size and weight I could see it being worth having to charge some specific items and then just toss it back in the bottom of a locker.
I know that I could go up to a larger unit, but that misses the point of having a small and unobtrusive unit in the first place. Let's face it, anything that weighs much over 50 lbs is going to stay right where it's put be it the garage, the bilge, or the back of the pick-up truck. At 28 lbs this is something that can easily be brought up on deck, walked down to the dock, carried ashore for a party, etc.... Frankly, I was surprised that they've gotten them down as small as they have with the output they have.
As usual, we have the camping, hunting, and fishing markets to thank for the impetus to design the product.