I've had the Dynavin N6 in my 06 E53 for two years now. The sound quality is excellent in my opinion. I don't have the professional background that you do, but I feel like even for the added costs this is a great option if you are not looking to do a wholesale retro of the entire system. It's very plug and play. The screen does wash in direct sunlight, but with the angle that the unit sits at in the E53 dash, I think your going to get that with just about any large display in that location.

Also, Jeff at JT Distributing is as solid as it gets on the customer service and support front. If there is something wrong he will jump through hoops to make it right.