I am assuming that everything will be better on the X, not that I'm saying my Droid is bad at all, I love it.
I have an after market Parrot bluetooth in my car. It works fine with my droid most of the time, syncs contacts, plays slacker, etc. But occasionally the connection does drop and I have to reset my bluetooth on my droid to make it reconnect.
I'm buying a new Camaro this summer with factory bluetooth so I am hoping the X works good with that.