golfdude:
I know they should work without any issues as mine has been excellent. vin # 13844. Over 11 klms and in -35 temps. (it is stiff as a board for about 15 minutes at that temp though) I have heard of a few guys with that problem but not all that many. You shouldn't have to put up with that, the dealer should give you a new transmission if you scream loud enough.
The stupid thing is, one dealer will treat you like a King and fight for you and make sure you get taken care of, no matter how big or small the problem. So even with some glitches, you will still love the car and the over all Xfire experience. Then some owners get the dealer who makes up excuses, tries quick fixes and make you feel like they don't care. Bummer!
My dealership is a good one! They bend over backwards for everything and they have told me that the last thing they want is to get a complaint sent to DC. Maybe you should try a new dealership. It doesn't have to be the one you bought the car from. Good luck!