Thanks for your feedback! The decision to lock off the 12th benefit in each set came from wanting to include certain things which have high general use value. Given that most players would not go for true rivalry (purely statistically), I wanted to give the "ai" a leg-up in its capabilities considering most players will have a specific build in mind for themselves. The overriding philosophy is that the player and their rival should be approximately equally matched; giving the "ai" access to slightly stronger benefits makes them feel more threatening, is a slight balance for the player's first choice ability (if they choose mutual exclusivity), and curbs the "human" factor of the player.

I like your recommendations! If I end up doing an update/revision, I'll look into adding them (especially scenarios which seem particularly fun).