I bought these to replace my beloved etymotic er6i that went tits up. I was disappointed by the quality and sound. They came off as tinny to me and with little bass response. I tried all the different ear tips with poor results. And there was no way of wearing a helmet with them--or at least not my arai.
I've yet to find a satisfactory replacement.
One of my coworkers LOVES his S4i so YMMV