Thought I'd share these as I just bought a pair myself. Most reviews put them similar to the X2s but with a less bassy sound profile.
As Fyrelor said: BUY AT YOUR OWN RISK. The X1 non-Ses have been discontinued since 2015, and with no info on the X1Ses linked other than a spec sheet I can't guarantee these are legitimate.
Good headphone. Work great with me from 2013.