From test flights after modding of pushmepullyous @ RSTOL, we determined that if you could read ANY instrument it probably meant you'd lost the rear engine (because you could see the front engine turning) and none of us (including my boss) liked the idea of riding around with 500 lbs of iron mounted behind us @ shoulder height.
Parts of the RSTOL system was included in the French type cert for the 337 (the leading edge cuff and maybe the stall fences but not the interconnected control system), The RSTOL main factory @ KPAE in Everett did mod an O-2 with a full kit and the results were pretty impressive, but the gummint said it was too expensive to implement, soooo, if you're ever cruising the boneyard and come across an O-2 with a leading edge cuff installed---------
