UCP (ACU pattern) is terrible at concealing people. (Unless you plan to fight wars exclusively in gravel pits or floral print couches.) Multi-cam is one of the best "universal" camos out there. The ACU (and AF ABU) patterns are failures, and the higher ups are starting to acknowledge it.
Put it this way, I can find people at 3-4x the distance when they are wearing ACUs/ABUs compared to woodland BDUs (the uniform ACUs replaced). ACUs/ABUs don't blend in!