I have them both and I would say yes, they are worth it. IMO the 215's just do everything better. The S4 might be a bit boomier, but the 215's have plenty of bass and the quality of bass is better to my ears at least (tighter/more accurate) with good low end extension. The only potential issue is fit. I've read that some people just can't get a good fit with the Shure's, but for me they are fine. They also isolate a bit better than the S4's.