I have owned the Trango S EVO gtx, and I now own the Trango Alp. I sold the Trango S after a few outings b/c I bought them a bit too small. I got the Trango Alp b/c they seemed to be a bit more durable, but they do weigh a few ounces more. As far a fit and flex go, the two boots seemed the same to me. Also, the sole on the Alp is a bit more aggressive with deeper grooves.