have not used the avid mm but, if history follows suit, am gonna guess it's awfully close to the 843.
in my hands, the avid mhm and the loomis cbr845 fish bad close to each other in terms of power and action...as does the avid hm and the cbr847.
any slight difference between them may come from the difference in handle lengths...the handle on the cbr series is an inch or so shorter than the avid handles...if the handles were identical, one would be hard pressed to tell the difference between them.