"Marginal" would not be the way I'd describe it. "Scale" is more accurate. The 1.70 is a wonderful engine and I debated quite a while before deciding to swap it out. One of the deciding factors was the fact that I needed so much ballast (in my case it was 26 ounces) on the firewall to make the plane balance. My thinking is, if I need more weight then I'd prefer to add weight in the form of more engine rather than just lead. Once in the air, the 1.70 is plenty and will pull the airplane through any maneuver appropriate for this plane - it won't hover and neither would the full scale Take off was the only time I found myself wanting a little more power in reserve. The 200 twin is an awesome engine and I would think it would be a great match but I have no experience with that one. Before I got the Enya V-twin I thought seriously about going with the new Saito 36cc gas engine. My 1.70 radial now resides on the nose of a Pacific Aeromodels clipped wing Monocoupe and is a perfect match for that plane.