After riding 2-1/2 years on my Xero XR-1 wheels, I am looking for an upgrade. The first reason is that my chain rode off the cassette and chewed every spoke on that side; the second is that I'm riding with some much faster groups this season and want every advantage I can get. My LBS recommended Ksyrium wheels, but another trusted source says those are crap. Any thoughts? Budget is around $1000, and I'm not racing (yet).