I think there are some advantages. No gas fuel, no noise, maybe less maintenance. Insurance vs. a genset should be different. I'm assuming you hook these up with a bypass switch, so you effectively have a whole home online UPS; this would eliminate brownouts and dirty/noisy power. I wonder if there's a power factor advantage on the utility side as well.
Yes, but do you think there would be any benefit in it there being less variability? Right now a utility deals with a bunch of random stuff drawing power, presumably at different factors. I don't know what the right language is to describe this, what I was thinking is that if everyone effectively had a big UPS then that variability would be seen by the UPS, and the power company would see a more uniform draw.