So that dealer does NOT sell Sunray products? It's all subjective...if I go out with ANY coil and find a bunch of stuff,I'm going to think it's a great coil,and it might be. But there's really little hard and fast scientific evidence that any other coil couldn't have found those things. Unless you have 2 identical machines tuned exactly the same but wearing different coils,there's really no way to know if your magic coil is,well...magical at all.
I've touted the Sunray stuff before so I'll save the spiel. As long as the one you're looking at is in proper working order I believe you will have very good success with it. To me,it's the perfect size coil for the E-series,as far as balance and swing weight goes. It's also,like you said,a mid sized coil that makes you feel that separation is good and coverage is acceptable. The X-8 to me is a coil that you CANNOT lose with,it has everything going for it. The build quality is high. There is no downside. Get it,use it,love it. And if you don't you can get your money back and sell it to me,I'd kind of like a backup should anything ever go wrong with mine.