We have a couple of people in our neighborhood with those types of generators and then they just hook up to the natural gas line for the house to feed it. If I were to build or do major remodeling then I'd probably get one myself. I just have a small 5.5k or so generator, had two but sold one to someone after Ike. I just use them really to keep the freezes cold.
Speaking of off road diesel and here in Texas, I filled up a couple weeks back at a Chevron and noticed it was red fuel. Ended up reporting it to the State.