I've been flying a Magnum XLS .52A 2-stroke for two season now. I had two issues with it when I first broke it in:

1) The remote needle valve assembly was leaking air, so I just moved the needle valve to the front and bypassed the remote assembly
2) The muffler bolts kept shaking loose and falling out, so I bought some blue lock-tite to secure them.

With those two minor annoyances out of the way, the engine has been running wonderfully ever since. My experience with my Magnum 2-stroke gives me no resevations about recommending Magnum 2-strokes at all.

I also purchased their RFS .52 and RFS .70 4-strokes from my LHS during the sale. They are both for projects I haven't finished yet, but I'm looking forward to trying them. I have an O.S. F-type plug and a Fox Miracle plug to try in them so I can see if the F-type plug is worth double the money that the Fox Miracle sells for.

I own O.S. and Saito engines, and it's funny to realize that cheap engines can run great while expensive engines can still be worth the extra money. The higher quality fit-and-finish aspects of the premium engines are sometimes subtle, but there are just minor considerations with cheap engines that you don't have to worry about with the more expensive models. Both will fly your airplanes very well, however.