I don't think Rigsby could kill so mercilessly. He gets too emotional, as in the episode when Red John killed the ffriend of his associate in Mexico.
Rigsby took one look at the bodies and ran out to throw up. He also is too emotional and protective of Van Pelt.

I also am beginning to think that the clues around Minelli are too obvious for him to actually be Red John. He might be, but it seems unlikely to me unless there are more compelling and less coincidental occurences. Incidentally, I really enjoyed "seeing" Red John in physical form last week.
For the first time, he became something other than a topic of conversation. He now is a person, albeit disguised, enveloped and monstrous. Keep the revelations and cluses coming!!