I'm still one for the option of removing threats and just pitting everyone against everyone like the original game, it solves every problem down the board. The matchmaking system also takes more than just your threat into account, your gun, gun mods, how many stars you have, rank, and character mods are taken into account as well, which is obvious when you're in a semi empty district, and change your loadout and stuff while waiting for opposition.
Edit: I should also point out that I believe the old system with Wins/Losses determining your threat was much better and made it much harder to gain and lose threat levels, the worst thing they ever did was make threat score based on the requests of elitist players that disliked having to use teamwork to gain gold.