I haven't raced in CO but concur, and will add that Nor Cal is pretty similar. Up until the UCI changed rules you'd have Levi, Brookwalter, Horner and whole teams Bissell showing up at weekend races. That will harden you up in a real hurry, and courses that aren't that selective are suddenly monsters. Heck, Lance, Levi and Horner showed up for the Nevada City Classic crit when he made his comeback. You still get domestic guys like Ben Jacques-Maynes (Pro Challenge KOM) toeing the line when not elsewhere.

Masters is also hyper competitive but more in road racing and less so crits than So Cal. Tons of former pros who have retired to geezer racing, which keeps you honest.