If you go the CR1 route it will do nothing for you on CO metal.

You are eligible for EUA (CO's version of UDU) on the CO flights even though they are booked as a UA codeshare. You'll be prioritized after CO Platinum Elites on the list. Don't expect to get one on the transcon as those are rare, even for a platinum.

If you had more time (or just for the future) it is a good idea to link your accounts with CO and UA to match status over. That way you would have been listed as a CO PLT instead of a UA 1K and you would nudge up a bit higher on the priority list. You can read more about that process here: http://www.flyertalk.com/forum/unite...tus-tools.html.