I'd have to vote for Shadowknights as the best duo class. With a monk you can't go full bore dps on the shaman. With SKs you have immediate and rock solid aggro. Plus SKs are better pullers in the majority of cases (in my opinion - having played both a monk and an SK, I prefer to pull with my SK by far ... even against casters). Plus you can break out the pet pull if you really need.
Anyway, SKs bring a bunch more to the table then monks, imo. Guaranteed snare is always nice to have, plus the mana + hp bite can add up in the long run. And while a monk is definitely more dps then an SK ... an SK + pet = 2 sets of spirit procs instead of 1, which brings the dps gap a bit closer (though still pretty far apart). But when you take into account that the shaman can pick up some of the dps slack, that the SK has a lot of self lifetaps that can be extended with AAs, yadda yadda yadda.
So I take your RMS method (risk management system?) and raise you 1 SK plus a skelly pet.