The CO card will become the UA Explorer card in a matter of weeks at most. So you wouldn't be able to get the card and bonus and cancel it soon enough. Also I think in threads it's been stated that anyone who got the CO after September will not get a bonus on the UA Explorer. The UA card will probably have a bigger bonus at some point too.

I just got the CO biz card as it's disappearing although it may well be converted into the UA biz card also keeping me from getting that bonus. Does anyone know when the CO biz converts and if the same same language is in the UA biz T&C?