The question is more along the lines of, what is the purpose of the generator? Temporary power or long-term whole house power? For a day or so, a portable one is more affordable. My neighbor has a Gentech whole-house unit, had to just have it completely redone, new tank installed. Has to run monthly just to keep functioning, very costly.
Well, I don’t know how old his is. I do know that they’ve come along way. The Generac that I had installed has a seven-year warranty. It does a self test once a week. The reason I chose to do this, is because we have had frequent power outages where I live, some for an extended period of time. I also travel a fair amount, and I don’t want to leave my wife having to drag a portable generator out, and plug-in where necessary.
As for the expense, we are fortunate to be able to afford it. I also think it adds value to the house, but not, obviously, enough to cover the expense.