I,m very happy with my HS635's but never even thought of using them on anything more costly than a Do,although I have put them on the smaller surfaces of a 10 lb'er (elev. halves.) I've used a dozen of them from 46 UCD,60UCD,68" YAK, H9 ST without any troubles,in fact, they still have very little slop in them,they wear better than MG IMO. On another note, I had to fly my 46 UCD this last weekend because I dorked my 60 again,was torquing at 10' and it flipped out too fast for me to handle it plus I still had spoileron mix on which didnt help the pull out very much. It was so nice out ,I actually flew the 46 which usually justs sits when I have the 60. I found out that in light wind, this thing isn't too bad at all for 3-D. It harriers as well as the 60(with the same modifications),it hovers OK but needs almost constant up-elev to hold it,I could add some up-thrust for that. I wanted to shoot some harrier landings but have 15" prop,it would certainly hit the ground even on a good one. I'm going to put the 60's gear on the 46,its a perfect fit for the holes and adds about 1" height. I had to settle for dragging the tail wheel a couple times in a harrier,satisfying, but I like to land it.