Ok, I just got the 903 - basically the same thing but without a bluetooth transmitter (for non bt enabled devices)
The headset is very light and confortable but also stable and won't fall out of your ears.
All the buttons are working as far as I tested so AVCRP is fully working.

I do have a question though:

Has someone tried to charge his 903/906 with the charger from N900 or USB?
thanks
EDIT: seems to work fine both ways

And for those of you who are comfortable with silicon earbuds (even those that came with N900 fall out of my ear) I found this:
Sony's HBH-HS800