Eclipse CD3200:
Was able to connect with the Pre for A2DP audio only, and the connecting was not consistent - sometimes it would connect right away, and sometimes it would not connect at all.
Was not able to make calls through the Pre, either (but it did work with my old Treo 800w.)
JVC KD-R800:
Connects with the Pre flawlessly and consistently, both with A2DP and phone profile. At first connection with the Pre, the Pre prompted me to allow the head unit to download my contact list - and boom! There they are!
Another cool feature is that the battery level of the Pre is displayed on the head unit display, next to the Bluetooth signal strength.
The JVC KD-R800 actually has two USB ports: one in the front, and one in the back. However, one of the ports is used up by the small USB Bluetooth dongle.
Sound is pretty clear on both ends while making a call.
Overall I am happy with this stereo, the only downside is that there is no provision for steering wheel control compatibility. If you want to use your steering wheel controls, you would need to upgrade to the JVC KD-A805 model, and a SWI-JACK adapter.