i cant speak for all engine types, i have a few small OS (a .10, .25 and a .40) all run really nice BUT i also havea magnum that i love to death... however its a 1.10 so i cant speak forthe smaller magnum engines. but i really like them, in my experiance they seem to have better thrust to weight than other engines ive playd with. and having hex bolts instead of philupsmakes it worlds easier to tak apart if you need to.

i also have a norvell .061, not thatsrelivent, but i love that engine too :-D

OS is a more reliable brand, but i would still take my magnum overit iffor no other reason then there built better and cheaper, my mag 1.1 cost what my os .40 cost :-s go figure