I use an XDA Orbit with WM6 and this pairs and downloads the phonebook into my Gen6 ULF OK.

You cannot pair one phone, download it's phonebook and then use this phonebook with a different paired phone, as the phonebook gets downloaded each time the ULF attaches to the phone.

There are two options - the 1st being to set up a phonebook in the VR system, so you can then say 'dial name' ... alternatively there is a bit of software that you can install on your XDA called Jetwaremobile (www.jetwaremobile.com) which should allow your phone to download phonebook, read SMS messages etc.

I used this for a while but since upgrading to WM6, don't have the problem any more, though SMS's don't go onto the ULF which is a bit of a pain.

You can pair up to 4 phones, and the ULF will auto-connect, but you need to remember that the last phone paired will have the priority, so you need to make sure that the phone you want to always connect gets paired after any others.

And we have no idea why the ULF's cannot be upgraded - only thought is that perhaps there is too much functionality based in hardware as opposed to firmware.