[greglepore]

Maintenance is simple on an aircooled genset-oil change (only like a quart and a half) air filter and plugs. Occasional battery swap. I had a company do my former 25k watercooled unit, but the current house has a aircooled.
FWIW, I'd go as big as budget allows for a couple reasons. First, having lived with a slightly undersized unit, it is annoying to not have almost everything available. The big unit I had in previous house, you never knew the power was off-everything worked, including the oven. This one, I lose a/c in the main house (we have 2 systems, one for master suite, one for house-could probably fix this with a soft start) and several circuits, including the one the freezer is currently on, because we moved it to a different room than builders. The other reason is as above-you're running the bigger genset at partial load, whereas mine is running all out. Still, its 17 yrs old and still running (knock wood).