I don't know how the ASP/Magnum blue head compares to the Enya 15CX. I don't know of any stats that would enable you to make that comparison, except that the ASP would certainly be cheaper. Given that the 11CX is a good engine and the 15CX is a bored out version, I have high hopes for the Enya, but hopes is all they are at this point.
I don't know what difference the ball bearings would make in either weight or performance. When OS was making plain bearing engines they were much less powerful than the ball bearing engines, and much lighter, but they differed in so many ways that the type of bearing was the least of it. Enya has made plain and ball bearing versions of what look to be the same engine, but sometimes they also have differences in the crankshaft or the carb. No idea what they did with the new 15CX.
I only saw a plain bearing 15CX on the Enya web page; where did you see the single ball bearing?
Jim