I've been in so many MF+ and FM+ that I'm confident to say that it doesn't matter the gender combinations or how many. What matters is how well every participant can work together.
I've been in very sloppy threesomes and very coordinated 6M+2F gangbangs. When people can't work together, it's a fucken train wreck (i.e. dicks go soft, positions don't work, alpha-wannabe-assholes, greedy participants, passive participants, jealous participants, bad hygiene or body odor, free for all fucking behavior, accidental bodily harm, and so much more).
Seems like everyone is in fantasyland thinking it works like in the porn movies and even there, it's still messy at times.
I could rant on this forever with stories that would make you cringe.