I have to agree also with the JX. I also run speeds and am very impressed with the JX motors. A good friend runs the JX and to me it's well worth the price with the crank coating, stronger case, and OS quality. I'm strongly thinking of adding one as well when the time comes.
I have to say that when i was running the RBS7, WS7, and the older C5 that after break in RB recommended changing out the rod. Also, if you broke it in cold, I've seen a S7 crank pin become elongated. This was a few years back when I was running RB's, they are good motors, and they may have changed since then. Just something to look into.