Hi
The Sony Ericsson K850i has worked out beautifully for me.
Handsfree
Contacts
SMS

I haven't tried Call Hold/Conference, or call waiting, but these functions are also supposed to be fully supported.

I haven't been able to locate a Snap In Adapter yet, but to be honest, I haven't been looking too hard. I think I can live without it.

The K850i does not have an external antenna connection so the cradle is only useful for the purposes of charging. I'll just install some USB power ports and use that for charging.