I had a neighbor run a similar load on one after Sandy, he got about the same runtime as well, they are definitely impressive for their size. On a side note, many of the street vendors in my work AO(downtown NYC) use them, one told me he gets about 3-4 days on a full tank.
I have a larger Honda clone(Generac GP5500) which I bought right before Sandy, and I ran heat (1/3 HP blower), full size fridge, chest freezer, hot water heater(electric ignition + direct vent, about 700w), sump pump(1/2 HP), and lights(indoor and some exterior security lighting), toaster oven and coffee maker, got about 10 hours on a full tank(7.4gal). I ended up getting a tri-fuel conversion kit for it,
you might want to consider one for yours. My next project is an automatic transfer switch and electric start.
As for National Grid, I can tell you a thing or two about them(ok, it was LIPA, but they sub-contract to National Grid)
Stay warm.
My .02