Watts/lb is always figured and calculated on Watts IN, not Watts out. You can easily measure Watts in. Watts out depends on so many factors that it's not humanly possible to predict it. Even the computer programs only make a rough guesstimate based on ideal scenarios.

That 99.2 Watts out figure is probably the result of 150-180 Watts in. Roughly 60 Watts/lb, which fits right in with the performance of the airplane as I've experienced it.

Keep in mind that calc programs are not all that accurate due to the countless variables that they'd need to account for to get a 100% accurate calculation.

The Watts/lb rules were originally developed by electric "guru" Keith Shaw, based on Astro Cobalt series motors, back before brushless technology was widely available and Astro Cobalts were the only alternative to car motors. Cobalt motors were/are roughly 60% efficient, somewhat better than cheap can motors, but not as good as a brushless, obviously. For your 100 Watts/lb, you can expect decent performance with a can motor, better with a cobalt, and "WOAH BABY!" with a brushless.

Pay little heed to the "full throttle flight time" figures. That's FULL THROTTLE flight times. You won't be flying full throttle the entire time, unless you seriously underpowered your plane. Fellows in my club regularly keep their Superstar EPs in the air for 20+ minutes with the stock power system catching thermals and soaring around. For regular flying, expect 8-10 minutes, right up there with a typical glow flight.