Let's see... 2700 to 500 psi, giving 2200 psi consumed from an AL80, which is nominally about 77.4 cubic feet when filled to 3000 psi. That gives 56.76 cubic feet consumed.
If he was on the surface at 1 ata and used that much air in two hours, that would make his breathing rate about 0.47 cubic feet per minute, which isn't at all unreasonable.
If he was at 33 fsw for two hours and used that much gas, that would make his adjusted surface breathing rate 0.24 cubic feet per minute, which would be more-or-less outstanding.
Going for the middle ground and assuming that with descents, terrain, ascents, and stops, he'd average 20 fsw (2/3 of his max depth) over the course of the two hour dive, he'd end up with an adjusted surface breathing rate of 0.29 cubic feet per minute, which would be really nice if I had it.
(If you assume he exaggerated slightly over the numbers, and actually had, say, a 3200 psi overfill, averaged only 20 fsw, and finished around 110 minutes, you start getting a little closer to *my* numbers on a rather good day.
)
When I started, I didn't hoover my tanks down, but I used air at a good clip. In the many, many dives since then, I've become proficient at buoyancy and trim, I've dropped all but three pounds of weight (when diving a neutral-at-empty tank), I've become one with the frog kick, and I've become completely at home in the water. None of those changes stuck out as exceptionally significant in my logbook (I calculate my surface-adjusted cubic feet per minute rates on every dive), but put together over, say, 50 dives, I can certainly see the difference. I easily use 50% less air than I did in my first dives.
One of the most interesting things I've found is that I'm often wrong regarding my impression of whether I'm sipping or hoovering. I have no problems estimating air time remaining, gas needed for ascents and stops, or what have you, but sometimes I feel like I must have been absolutely burning through my tank. Then, when I do the numbers in my logbook, I find out that I was actually within a percent or two of normal, and sometimes lower than the last dive (where I felt like I was positively sipping air). Having a computer (wrist computer, not air integrated) to tell me my average depth so I can run accurate surface-adjusted air consumption numbers every dive has really helped me understand my air consumption, both in how conditions affect it as well as how sometimes my gut feelings can be quite undependable.