European, I posted almost the same post as yours last week- same circumstances, just different home base, etc.

I completely concur with Worldpilot- just did the exact same with CO.
Problem holding my status match up is that Delta "recognized " me as Gold on Dec 12 but has yet to send Gold Medallion packet to me. I even went as far as to ask CO if they could use my Silver card for now and then again with my Gold next month, and of course, no dice- just once.

So, now that I am about to make some trips starting 2 weeks, I will be going on CO as a 1st timer, which should mean nothing but no chance at upgrades to 1st. Ironically, my trips will be on UA metal, but branded with CO flight #, not that it would make a difference either.

I chose CO over UA based on what I read here about *NET award booking AND the fact that I walked into local Chase Bank last week and signed up for a debit card (25k miles) and a CC (35k miles), so I will have 60k miles without even stepping onto a CO plane.