Here below my first impressions: (Sorry for my English!)
Build quality: Shure are better done than Westone, they looks stronger and the looking appeals to me. E500 box is nicer and full of extras (PTH, Volume regulator, some cables, a complete set of tips...)
Comfort: They are both comfortable, but I prefer Westone, cable is thinner and they fit better into my ears.
Sound
My source is an ipod nano 1st gen with apple lossless files + Silvercab by Qables
Reference albums:
Jagged little - Alanis Morissette
Alchemy - Dire Straits
Back to Bedlam - James Blunt
Aerial - Kate Bush
Il Mucchio - Biagio Antonacci
Tra un manifesto e lo specchio - Francesco De Gregori
Treble: Shure is more brilliant and it is less sibilant (this is the main issue of Westone, in my opinion...)
Mids: Shure deliver a more detailed sound, but it depends on source...
Bass: Westone's bass is warmer, more enjoyable. On the other hand, shure has a more detailed and precise bass. Sometimes, Westone bass melts...
Soundstaging: Shure has a wider soundstaging, channels are better separated and especially with headphonia you can distinguish every instrument...
Source influence: When you use Shure you can easily hear the difference between two amplifiers or sources. I have tested them with x1 and headphonia and I've noticed a strong difference between the two amplifiers that I hadn't appreciated before with Westone... (For instance, with headphonia,i've heard some details that i hadn't ever heard before...).
Surely Shure fits better to Headphonia than Westone!
Conclusion: Shure deliver a better sound but they miss a sort of magic that Westone have. This is only my first impression. Let me hear the new cans longer and maybe I'll change my mind...!