RE: Evolution 60 NX in a 40 size case...
Look at the replacement prices of sleeves and pistons between Evolution and OS, and that may make up your mind for you. In case you crash the engine some day, compare prices of the crankshaft and case.
The reviews by Clarence Lee pretty much validates the same quality between both brands in the other sizes. I would give Evolution the edge for using chromed liners, and the 3 year warranty.