Be sure about that. Not only do you get full EQM for booking on CO.com, but you also can get full EQM on some corporate travel reservations. Starting a couple months ago many of us starting receiving full credit for travel booked through work. There were a couple threads on it in the CO forum.

Having said that, since you put that leg room was one of your priorities I would steer you away from CO if you can only get silver status. You cannot pre-select exit seats with silver status on CO (I believe plat and gold can), and Y in CO is IMHO very uncomfortable for long hauls. UA may be better for you with PE. CO also only flies to CNS in Australia, but has nice access to Central and South America from the Houston hub.

UA or AA might be more aligned with your needs.