I realise it's been a long time but really you people don't have the right to tell fans to "move on".
However unrealistic their expectations, their perseverance is commendable, perhaps more of us should fight for things we love. That Whedon is distancing himself from the movement at this early stage is unfortunate but understandable, for exactly the reasons stated above.
In response to those saying the fanboys would never agree on what should be in the show or they would never like it as much as the original, I think that Firefly is a true exception to this rule. The TV show was never about having the right vehicle ID on the side of the ships, or color coded uniforms, it was about detailed characters and the moral challenges they faced - always together. The fans don't want to rate episodes or whine about canon and non-canon, they just want to see Serenity fly again.
If this project has even the slimmest chance of working then good luck to them, and when the time comes even I might put my money where my mouth is.