Ok, have about 14 hours on these now, they've opened up a bit and sound much more like/same as the the ones I used for demo in the store. The biggest change though, and it is remarkably noticeable, is the bass response - it's toned down, much tighter, less flabby, less resonance/boominess. They are just sounding insanely good to me right now.
Listening to Tool - Reflection from Lateralus was over the top yesterday, there was almost painful SPL's beyond a given (relatively low) volume, but today it sounds much more accurate and the drums are much tighter and I can enjoy it at normal listening volume.