the music turning off when going in reverse is in the V4 unit as well and discussed in Jeff's other thread. so that isn't new. It is something that people found out when they started putting the camera in and jeff confirmed it was supposed to do that and is more of a safety feature.
it may be personal preference, but when the phone rings or I am talking, I want the music off. right now without BT I am constantly turning it all the way down before I make a call or answer one. I can't wait to get this unit. It may not be perfect for everyone, but nothing is ever perfect. I have a pioneer avic d3 in my cobra and at the time, those were so damn good and everyone raved about them. there is plenty with it that I don't like, but I deal with it because overall it gets the job done and is a very nice unit.
at least with dynavin, when the people talk, they listen.
BTW, I sent you a pm about a DIY thread.