Here is a computer run done with raw unchecked data from Jeff Jakob. The run may be understated as the thrust curve has not been verified to flight data.
Jeff Jakob 9-20-03 Black Rock Hybrid
8x216" CDr 0.55 250 lb init 125 lb pro (adj) 9KS 2500-HYB-N2O/HTPB 86.7kns(61%)Q9637-HYB-N2O/HTPB CDA (IN^2)=27.65 Temp 90F pressure 27 inhg no wind vertical ORBIT.BAS COPYRIGHT JERRY IRVINE WEIGHT ALTITUDE BURNOUT BURNOUT MACH ALT COAST (LBS) (FT) ALT (FT) VEL(FPS) MI TIME--------- --------- --------- --------- ---- --- ----- 250.0 31323.0 12227.6 2029.3 1.9 5.9 30.4 300.0 29806.5 10200.2 1788.0 1.6 5.6 31.7 350.0 27503.1 8663.7 1532.3 1.4 5.2 31.8 400.0 24964.3 7479.7 1334.0 1.2 4.7 31.1 450.0 22434.3 6534.4 1179.4 1.0 4.2 30.1 500.0 19617.1 5744.6 1046.8 0.9 3.7 28.4
Flight mass was 252 lb.
As you can see the rocket can carry a considerable payload with minimal performance loss.
Just Tech Jerry