Late reply, but I only occasionally stop by.
We have a Generac at this house, had one at the last house, and my parents have one. My previous one and my parents' I did the physical install and the control wiring. A friend who does that sort of thing installed subpanels and a plumber did the gas connections. We bought both units at Costco (the same week--we got a few looks and a nice rebate check that year!) This house came with one which is a few years older. I do the annual maintenance which is pretty simple and economical, mainly cleaning, checking, changing oil and filters not much different than a car. My parents have a Mobile Link unit on theirs. I get texts whenever its state changes or if it would detect a problem. I wish we had that but its not compatible. Ours is good peace of mind for my wife if I'm travelling, which has really declined in recent years, knock on wood. Its critical for my dad who is reliant on oxygen and is homebound.
The previous house one and my parents' are both 16KW units which power 100A subpanels. That allowed feeding about 3/4 of the house but not outbuildings at each. We selected circuits to move to the subpanel to maximize comfort/safety/security. This house I have a 16KW and the transfer switch sits between the meter and the main panel, but I don't have an outbuilding here either, unless you count the unpowered 12x12 shed. Old house ours ran a 3T heat pump no problem summer or winter, though in the winter that didn't make sense since we had a natural gas furnace for backup. My parents' runs their 6-headed Mitsubishi split system no problem. Both houses had wells, sump pumps, fridge, freezer, etc on them. The newer units can automatically interrupt an HVAC compressor if they need to.
Our power consumption is probably pretty low if the AC isn't running. Our entire house is LED except for 720W of candelabra based bulbs in a chandelier in the foyer (which I finally ordered LED bulbs for) and a few fluorescent strips in the garage and basement. Guessing our next biggest load is a dehumidifier or the washing machine. Or maybe all my IT gear