I don't like RPS.
RPS works in RTS games because you're not really being affected by the balancing. Your units are getting slaughtered, not *you*. The impact of RPS doesn't really have a personal affect on the player.
RPS in an action game like MWLL or a shooter just frustrates and irritates players. An aspect of RPS is feeling completely helpless, being unable to defend yourself from other players, and these are feelings that are toxic to the longevity of a game. When only 20% of your new players are masochistic enough to endure being exploded instantly from across the map because they haven't learned the rather advanced tactics to defeat a Long Tom yet, that means you're dropping 80% of them due to your game design.
I simply have never known RPS balance in action games to be beneficial.