I know that the game is still very early in it's development process and a lot may still change. But I'm afraid that id Software is killing their chances of filling the 1v1-FPS spot in world of eSports by allowing different champions to be played in duel mode. I don't dislike the idea of different champions, just not for duel. One of the strengths of duel was always it's even playing field. Both players have the exact same conditions when playing each other. Your skill alone determines the outcome of the match, how good you are at the different aspects of the game. What happens if you add champions into this equation? Let's take the newly revealed champion "Anarki" and take a look at his ability:

<Health Injection> Anarki instantly heals himself and receives a permanent boost to his maximum health. Anarki also receives speed boost for 5 seconds after he used an injection. >> Official ability showcase video

To make my argument a bit more streamlined I'm going to completely ignore the huge implications the other benefits of Anarki's ability beside the heal will have. By giving a champion the possibility to heal himself you instantly let him circumvent core mechanics of the game: Managing your stack, being aware of your opponents stack, value of item pickups, risk management etc.

Managing your stack.
With his ability you don't need health pickups anymore. You not only remove a resource (health) as a core mechanic, but you also remove required movement on the map. This has a huge impact on the dynamic of the game and how maps are going to have to be designed. Overall fewer decision have to be made.

Opponents stack.
If your opponent is Anarki, he has full health. No need to deny health bubbles or be aware of his stack. Fewer decision have to be made.

Value of item pickups.
The Megahealth will most likely always be picked up at it's maximum effectiveness, thus making it even more important. Balance between the value of health and armor will be skewed, fewer decision have to be made (MH > RA in all scenarios).

Risk management.
By giving the champion the possibility to always give himself health during a fight, the reward of playing aggressively with Anarki is going to be way too high. This doesn't really present a problem if both players play Anarki, but it again does remove the difficult decision of aggression versus defense.

These are just some examples of how champion abilities can create "artificial imbalance" in the game. I didn't even mention the difference in maximum armor/health, as well as passives that alter the movesets of the champions. If id Software really is aiming for a competitive duel mode, why would they actively change an already balanced format? If the differences between champions is apparently "minimal" and is not going to have a huge impact in the game, why even bother with them in the first place? That's just bad design in my opinion. No matter how you look at it: If the abilities have minor impact, why dilute the game with them? If they're strong with huge impact in the game, you will only create an imbalanced game. There is no middle ground with abilities in the deathmatch format.

It is important to understand that I'm arguing from a standpoint, that one can use up to three champions in duel. If there was no selection possible, i.e. only Ranger can be played in duel, then the playing field would be the same. I want to point out again, that I'm not against the concept of champions in Quake. I see them working very well in different game modes, but I just don't see them work in duel. I just hope that id Software is going to listen to the player's feedback during closed beta.