Hey Terry:
It may help to understand all this engine stuff if you Google a bit for "speed torque curve". Hopefully you'll find something informative: I know what you want, but I don't have time to sift through results.
Basically, any engine, whether it's diesel, 4-stroke, 2-stroke, 6-stroke, big, small, or whatever, tends to have a torque output that starts out moderate to low, rises as the engine speed rises, tops out at some value, then falls as the engine speed rises further yet.
The power output of an engine, or any other rotary mover, is proportional to speed times torque. So the power* of an engine is equal to speed times torque times some constant. This means that if you have a torque vs. speed curve, you can make a power vs. speed curve. In all but the most obnoxious of cases, an engine's power peak happens significantly later than its torque peak. When people talk about using different propellers, what they're telling you to do is to try to find a prop that puts the engine in a happier spot on its torque/speed curve in the air.
Two-stroke engines that are designed to handle easily tend to run out of poop (torque and power) at a lower RPM than engines designed for lots of power. Cross-flow scavenging tends to run out of poop earlier than Schnuerle ported engines, given the same timing and intake geometry. So its to be expected that two sport engines, one Schnuerle, one cross-flow, would behave differently at high RPM.
* What a lot of people perceive as "power" in a stunt engine can be different. Brett buck has explained well and at great length elsewhere on Stunthanger. It's worthwhile reading.