extensive MP3 handling via Bluetooth

The audio/nav system with HDD has the option to connect to a MP3 player through Bluetooth. According to the manual it should be possible to scroll through the content of the BT audio device with the SEEK/TRACK buttons.

This requires a MP3 player with BT and high enough versions of the A2DP and AVRCP protocols (especially AVRCP as I understand it).

Has anyone got this working and with wich MP3 players?
There are a lot of posts on the iPhone, but what about the iTouch, Cowon S9 and other MP3's?

This seems to be equally functional as the USB interface (and a better investment?)

iTouch has the same OS bug as the iPhone (which I do not believe was fixed in the recent 3.1 OS release). The others should work (absent their own bugs)

I'm struggeling with this.
I've tried to connect my HTC Kaiser (also known as TyTN II or AT&T Tilt). It's set up with both A2DP and AVRCP, though I cannot find the version numbers.
When I play music from this device through the audio/nav system I'm NOT able to browse or search through my mp3's. The only thing I can do is to pause or resume playback.