A new CU study came out that claims that humidified baseballs don't change things much...
BBTF's Newsblog Discussion :: Nature News: Physicists show humidors fail to alter ball aerodynamics
Personally, I think it's garbage research. I suggest reading the comments at the above link. Mine (#47) mentions the change in compression of the balls. Another one (#59) shows the MGL flyball data, which indicates that the Coors advantage has been cut in half in recent years.
Hopefully, the Rockies braintrust won't take this study too literally, and conclude that the humidor doesn't really matter and stop using it. It's a fantastic invention for our environment that does have an observable impact, one of which being that our road performance has improved with a lower hangover effect. Another one is grip of moist baseballs allows for better command. This research left a lot to be desired, IMO.