I've always thought it would be Brett Stiles but this theory does make sense too!! There are 5 remaining suspects assuming the 2 dead ones are really dead, and I do believe they are dead. Here's my take on the remaining 5.
Assuming Rosalind is correct in her descriptions of Roy Tagliaferro obviously Bertram and Reed are out. I don't think it necessarily excludes Brett as age would be a bit difficult to gauge being blind. We have to assume that Red John is both intelligent and powerful. The Sheriff played dumb in the first episode and was overly clever in his last episode, I imagine he's somewhere in the middle, but he doesn't have the power or influence to be RJ. Bertram fits the power and intelligence mold, and also likes to quote William Blake yet doesn't fit the physical description. Reed is neither clever nor powerful and doesn't fit the description. That leaves the two most likely suspects as being Ray Haffner and Brett Stiles. Ray I thought was a bumbling dolt in his first appearance yet has proven to be clever conniving and resourceful in his recent episodes. He certainly fits the appearance Rosalind described and seems the most physically capable suspect of carrying out the murders. I also wouldn't be shocked if he had a tattoo, where as a tattoo on Brett Stiles seems far less likely. The negatives would be an affinity for classical piano, and the fact that he seems more a follower than a leader. I can't imagine him being smart enough to match wits with Jane, let alone be a top of the "Tiger Tiger" power pyramid!! The last thing is he doesn't have the same talent for reading people like Jane does, which makes it doubtful he could manipulate Jane the way RJ so masterfully has. Which brings us to Brett. Maybe this is what the Heller meant when he said fans will be disappointed, because Brett is the most obvious. He fits the Power mode better than the rest of the suspects. He clearly is the most Intelligent of the suspects. The physical is right on except for the age description by both Rosalind and Sophie. Rosalind's can be explained away by the obvious fact that she's blind, but whose to say that Sophie met the real RJ. I doubt that the real RJ would be so careless as to leave real clues in her therapy sessions. She could've been talking with Ray, on behalf of RJ. If either Brett or Ray is RJ, then it's not a coincidence, they're working together. They could be father and son, or master and student, but they're connected!! Brett is on a equal mental plane as Jane and appears more than capable of manipulating him and others. It would also explain why he knew that " Red John was planning a little surprise for Kristina Frye" and where Jane could find her. If Brett is not RJ, then he certainly knows who is and the Visualize organization is the key. It seems to mirror the Tiger Tiger organization. Lastly some final thoughts.
Lisbon did have a weird smile on her when Jane revealed the final clue (tattoo), almost like she's seen the tattoo before. If Brett and Ray are in it together, maybe Ray put the bug on Cho for RJ, and killed the girl as cleanup