my mother in law in new england has one. change over is flawless. runs on natural gas when it is turned on, certain of the appliances are turned off. i do not know what it cost, but it was expensive

a frined has a similar one, runs on propane. crossover is flawless. cost a bunch.

i have a 8-9000 watt gasoline powered generator. has 4 2000watt outlets. with extension cords, i keep everything excepting the electric stove and oven running. i use a gas grill and oven and a toaster oven. the generator burns about a gallon of gas an hour. that's 20 gal a day. lots of attention. if you do not use the thing, the gas gets bad, so one must use it or drain it. if i had it to do over again, i would get a diesel unit, or get hooked up to the natural gas line.