Mbuna aggression isn't necessarily dependent on the gender of the territorial fish.
Female socolofi's can be just as aggressive as the males, particularly full grown females. I've seen my 4.5" female socolofi's win domination bouts against 3.5" sub-adult male zebras. I've never seen a dominant female socolofi challenge a similarly sized or larger male socolofi in my tanks.
Regarding mouthbrooding, I've observed female pseudotropheus demasoni's which become slightly more aggressive when they're mouthbrooding (usually toward other female demasoni's) when they're mouthbrooding.
Of all the mbuna species I've kept, I've found female vs female aggression among metriaclima msobo's (for some reason) to be the worse.
Rift Lake and Reef tanks.