I think Tony's numbers are close to real world figures.

Gsmurfs comments are right on. For simlilar thrust, fuel consumption remains linear not only on one engine, but from similar from engine to engine. If you want to see the math, look at Schrecklings Turbine Bible, Chap 4&5.
The JetCat ECU spits out pretty accurate fuel consumption/run. I only have to spool my P-120 to about 75-80 K to get 12 lbs thurst. At that RPM, I burn 6-7 oz/min. I routinely fly my HotSpot agressively for 6 min flight time, and 9:30-10:00 min total run time and I burn 1900-2000 cc or about 65-70 oz. After comparing my fuel consumption to another fellow flying a 500 on a HS, it is nearly identical, since he has to be at full throttle to match my performance at 2-3 clicks about 1/2 throttle.

RPM vs fuel consumption is not linear. For our turbines, fuel consumptions begin to approach exponential, rather than linear increases above 125,000 RPM. That's why full scalers try to cram the biggest, most fuel efficient (hi-bypass turbofans) into their planes, and spin them at as low an RPM they can.

Since engine prices are coming down, it seems to makes more sense to get a P-120, or RAM 1000, or SimJet 3000, to power your BC, Roo, or HotSpot, since you can loaf these engines along at 78-80 K and EGT's around 450C, and still do 160 MPH It's RPM and temps that really influence time before overhaul.

Tom