Regarding the payback period, C/Net is also running a separate article today on a company trying to make home solar systems more affordable by making them easier to assemble and install. Anyway, in that article, they report 8 years being the typical breakeven point for your typical home solar electricity-generating setup, so this system compares favorably to installing a solar system.

For a system meant to be used daily, with little muss-and-fuss, this natural gas powered system sounds great. I agree that diesel would be great, too, particularly in a pinch, but under normal circumstances, I think I would prefer the ease and clean-burning characteristics of the natural gas way. I'm thinking it would provide heat plus electricity for blackouts that don't also knock out the natural gas supplies, which probably includes most blackouts in developed areas.