Most definitely not 800. Hot for a gas oven for sure, but not that high. I haven't timed a pie coming out of Dom's oven (the only real way to judge heat in my opinion), but I would guess its running somewhere around 650 degrees. 100 degrees doesn't seem like much, but I have always found that the end product is really quite different in a 550 vs a 650 degree oven. The blend of cheeses he uses really lets him leave the pies in there for a long time, and that well baked look makes people think he has a hotter oven than he does.
I was very lucky to work in brooklyn for a few months this summer, and even with Dom's very quickly fermented dough some of the visits to Difaras were really special. I could sure go for a slice now!