I honestly don't understand why Daemon needs Sleep. He already gets a damage boost upon leaving stealth, I think as a bonus to an ability that's already really strong in itself because it gives him a surprise attack advantage, that's more than good enough. Alternatively, make the damage boost after stealth a mod.
What if Safe Zone made team members immune to launchers? When I play Mekko I feel like my worst enemy is Makutu who can just run up to me, launch me and then the entire team pummels me to death. This would also indirectly nerf Makutu a bit without touching his values and reinforce Mekko's role as a defensive, protective tank.
While I agree that a cool guest character could increase the game's visibility, I don't think Halo, Gears or Banjo fit the style of the game at all.
Out of their entire back catalogue I feel like Enslaved's characters fit Bleeding Edge's aesthetic the most. Monkey would be a cool tank, Trip possibly an interesting support. But if I remember correctly neither Ninja Theory nor Microsoft have the rights for that IP unfortunately.