Not much I'm afraid. I did listen to a 6p awhile ago but don't think I had a good enough seal. From what I could tell (and take this with a massive pinch of salt) I think I would have gone the bass version, in the end I didn't get either.
They might have withdrawn that option though. I enquired about a recable for my micro's and CE said they were having a few problems with that type of connection. Your best best as ever is to get in touch with them to see what's up.
Not sure if it is still going but there is a Custom Art demo tour going round the states atm. Detail's are http://www.head-fi.org/t/741770/customart-us-ciem-demo-lineup-tour-including-harmony-8-pro
Maybe it's not too late to put your name on the list and have a listen to the models.
Got my music one's back today from 3rd refit. Will be able to let you know about rock (Magnum, Marillion, Pendragon) and metal (gandalf's fist and Alestorm) later in the week if you are still interested.