This is to Jedi,

Putting any high thrustline power unit on a modern flexwing or an Atos type glider would be a very bad idea. Modern wings have very little pitch damping (not to be confused with pitch stability -- stability and control damping are different things). With a high thrustline you want heavy pitch damping -- which my old '78 glider has in abundance. Likewise for yaw damping because the soarmaster unit puts the propeller disk some distance behind the center of mass of the system. In certain flight situations the disk can use the propshaft as a lever arm and 'walk' the nose around in yaw, which initiates a cascade of very negative events. I personally experienced this cascade multiple times in different 'glider + powerunit' combinations, and some of these combinations were truly horrifying in their instability under full throttle. I also personally witnessed two fatal accidents that began with these cascades. The gliders in these events were always the ones with the least damping in pitch, roll, and yaw.
The '78 wing I have in storage was intended to be a trainer/entry-level glider, and has massive damping on all three axis. More damping than any modern wing. This would make it a lousy mountain glider, but it worked great under full power soarmaster.