The only reasons I chose to accuse Jane is, 1.) I had to choose someone and 2.) that was his voice coming from the back seat of the limo.

Of Course -  This would conflict with the fact that Jane was sitting in the passenger seat of the car.

Even if Jane doesn't end up being Red John, for some reason the producers used his voice as Red John in the finale of last season. 


My reasons for this are the following:

1.) Jane's voice rises in pitch during certain situations, and if you compare these instances to the RJ recording in the limo, they are identical. Everything from the tone, the manner of speaking/pronunciation, and over-all phonetic acoustics of the voice.

2.) I ran them through my voice recognition software (torrented), and although their pitches differ, they have identical baseline signatures. 


Conclusion

I don't believe Jane is Red John, but for some reason they used Simon Baker's voice in last season's finale.