I don't think Alien Mind has been played much (at least not by people who were later inclined to post on BGG about it). I've never tried it because the vast majority of my GD games are solo (don't have a dedicated group to play with, so if I'm playing with other people it's mostly on Mission 1, and anything beyond default alien AI would be too complicated).
Haven't tried Alien Mind either as I enjoy the full coop of this game. If I want an alien mind I'd rather go and play Descent. However, Galaxy Ball is indeed tremendous fun and not just a cheap scenario slapped onto the base game.
I would only use this variant if there were more than 5 players in the group. This game is already great as a purely co-op experience, and I feel like changing it to team vs. 1 would change the feel of the game too much.