I bought the Sprint Treo 650 when it came out because it was the fastest way to get a 650. However, my employer's corporate plan is through Cingular. My question is, does the Cingular version of the 650 with the latest ROM update support DUN and the latest Bluetooth Car Kits (specifically BMW)?

I'm going to be traveling overseas and my options are to just keep the Sprint 650 (not being able to make calls there) and take my old SonyEricsson T616 with me to South Africa or to go with the Cingular 650 which appears to be Quad Band capable? If I go with the Cingular 650 I can live without the DUN, but I don't want to give up the latest car kit support. I guess another option would be to get an unlocked GSM 650 which does support the latest features, however would I be able to take that phone into a Cingular store and get my account added to it even though I didn't buy it from Cingular? My current SIM card for my T616 is from the AT&T days before Cingular bought them out and I was told that that card would NOT work on a 650 on the Cingular network.

Recommendations?