Your ST engine is more than adequate to power your H9 edge. I have a Lanier edge, and power it w/a ST 2000 (25cc), and it flies it great. The planes are similar in size and wt. Be careful flying your H9 edge in "slow flight", I have seen 3 of them tip stall when the pilots tried to land them too slow. I peronaly think the wing Sq. ft. is too small for the plane, but they seem to fly OK as long as you keep the speed up. In any case good luck, and don't worry about the engine, you have a good match.

Hope this helps, Bill