A lot of my concern about those issues goes back to our infamous
October Snowstorm in 2011, which instantly became my design basis outage. My folks, my kids and a lot of my friends were without power for over a week, some well over a week. I took care of both my folks and their neighbor by sharing one of my fleet of 3,500 watt generators for 8+ days. Obviously, we did a lot of wire switching to be able to cook, heat the houses and keep the lights on.

On the positive side, that little generator sipped so little fuel that it truly amazed me.
Some friends with permanent whole house generators did just fine, others not so much... but again, they were not all Generac products so I can't honestly say how the Generac-owning folks made out. I just know that there were failures and those folks had to scramble to find portables. It was not pretty.
But in regard to the propane cost issue, I seem to remember whole house consumption numbers in the 3-4 gallons per hour range. So for my 8-day design basis outage, that's maybe 700 gallons, give or take depending on load. That's a lot of money to a poor old retired poverty case like me!