I have pretty much monitored all custom minifigure manufacturers out there. I will admit that custom moulds were something I didn't believe could be adequately done, until I got my hands on Christo's Batman II Custom Red Robin. If I posted that Red Robin on a sight like this, with a tag line like 'new Red Robin to be released in 2014' the same discussion would be going on about it's validity. I'm not saying this because I don't believe you guys can figure out if something is fake or not, I'm saying that this minifigure is impossible to distinguish. If Lego made a Red Robin, it would look like the Christo designed minifigure.
With that said, Christo is the only custom designer out there that I know of who's making custom moulds of that quality for the Superhero and Star Wars line. And most other custom designers wouldn't go through the trouble of making a custom mould for something, that would cost them big bucks to produce, just to mess with people on the web. They would be quick to start selling them on ebay and a line would be drawn quickly to whether or not it was a custom design.
So, my conclusion on this, as well as the Joker that was leaked, is REAL! Which is awesome, because there are supposed to be a couple sets to come out next year that will feature Robin, and hopefully Batgirl will replace Robin on some of those sets, because we really have enough Robins already. I don't have a problem with Robin, it's just there are so many other characters that should have already been released, it would be nice to get some of them.