Not a bad idea, but thats a lot of work. To make this effective, the Disputees will have to (upon signing the Binding Resolutions) release any and all forms of communication between both parties (this shouldn't be a problem since most intelligent people keep all PMs regarding a deal until it is complete), provide photographic evidence of issue(s), and of course the biggest one of all (and hardest to prove/disprove) not falsifying information.
If possible members asked to be an Arbitrator not come from a place anywhere near the two individuals influenced by the dispute to avoid any biases. Maybe (although it is rather useless to even do so) ask a few members to provide character references.
This is a decent idea, but can it work...
If practice makes perfect, yet nobody is perfect... Why practice?