I have the non cd/dvd version of this receiver (XAV-AX100) and it's great. I've got the usb routed through to my center console which I was able to find a header built just for this purpose. I also have the mic routed through my glove box to the center console where it is just resting.
I've used this receiver for about 9 months pretty much exclusively using Android Auto for Waze and Spotify. Waze has always been pretty solid on Android Auto, but Spotify needed a little more developing (which it received) before I thought it was fully functional. The six touch limiter that Android Auto has without the parking brake really really kills the experience though. Anyway, issues with Android Auto shouldn't reflect poorly on this unit at all. The actual UI is pretty good and the bluetooth functionality is way more reliable than my previous unit.
I do not have aftermarket speakers in my car so I can't speak as to how well that works, but this must be able to push pretty far as I usually have the volume set to 25 and I would be reluctant to go much higher than that as it is pretty damn loud.
I will say though that for whatever reason I've never really been able to get the mic to work all of the time. I was able to respond to some texts soon after I got it, but either through the normal UI or Android Auto I've never been able to get the mic to work for calls. The person on the other end of the call can't hear me. I've not taken the unit out again to make sure the connections are solid because this functionality is no longer important to me as I'm not driving across town for my job anymore.
One of my friends had one of these in his Mk5 GTI and it worked so well that I just had to get one for my Rabbit.