Intel Ultimate-N 6300 with just two antennas

I've searched everywhere but I can't seem to get a clear answer.
What I'm seeing is that the Intel Ultimate-N 6300 can work with just two antennas but my questions is:

Does the Performance of the Intel Ultimate-N 6300 with just two antennas = the performance of the Intel Ultimate-N 6200?

I have a Asus G73JH so installing a third antenna would require me to completely take the laptop apart (voiding the warranty) which I probably don't want to do.

Could I just throw the third antenna in there without running it parallel with the other two antennas?