Honestly, I'm not so sure how Blizzard will implement all of this. D3's a PvE loot game first and foremost, so that's what they should be focusing on the majority of the time.
Also, with PvP as of now, there are no rewards whatsoever involved with the duels. Bragging rights? Hardly, if you're a well-geared player stomping people with half your DPS and EHP. Aside from the nonstop deaths, there's really nothing there rather than killing time and theorycrafters getting their fill with numbers and build options.
Until they implement some sort of rewards system, there's no real reason to complicate things by setting up dueling options when no one's really getting anything out of it besides... dare I say it, mindless entertainment (or torture if you're on the receiving end of the stomp).
If it's a suggestion, one way to go about doing it is matching people based on similar DPS and EHP according to an unbuffed armory profile, and then locking all gear in place once the game starts. This will involve retooling the armory system to feature only unbuffed stats and also the "item lock" mechanic that people keep wanting.