There are many good, interesting comments and theories here, and it's always stimulating to read others' observations.

I really do not know who RJ is, but based on the last episode (The Great Red Dragon), but I believe the following:

1) I still do not believe RJ is one of the seven on the list, for the simple but compelling reason (at least to me) that PJ would NOT have revealed his actual suspects to Lisbon and (by extension) the CBI team, since he had to know that telling one was effectively telling the whole team.  For one thing, he would not want them in danger, nor could he contain potential unintended leaks by any of them. However, we know all seven are "bad" in some way or another, so investigating them could prove fruitful even if none was RJ.
2) There have been so many twists and head fakes on the show that we are prone to doubt everything and be unsure of what's true or false.  Every recent death, for example, has been legitimately questioned, and we Kirkland has a twin, just for good measure!!
3) Bertram is NOT RJ, but his first lieutenant/first officer/prime deputy.  Though Jane only told the five suspects where and when to meet him, we have no idea if any of them told someone else.  And Bertram was always quick to make a call when he got key info re RJ.  
4) Who fired the shot in Jane's house, and who set off the bomb?  My opinion is that someone told RJ of the meeting, and he had a bomb placed into the house beforehand. Why was Bertram unharmed? (Everyone else is either dead--we assume, tsk tsk--or injured).  Bertram escapes unharmed.....why,  unless he knew where the bomb was and had been in touch with the 'bomber" (RJ).  Why would RJ plant a bomb?  To get rid of several problems at once, including PJ!!!
5)  I like Mashburn but he has so many characteristics we assume of RJ:  resourceful, very sharp, loves games, is bored, has high-level govt/law enforcement connections, and charismatic.  (Remember he is the only man we ever see Lisbon with in the series, which could help explain why she has been spared when she could have been killed.

Anyway, as they say, keep those cards and letters coming!! It will exciting to see the RJ finale, and we can only wonder how  the CBI and Blake Association story lines evolve post-RJ!!