Couple reasons I would go X2 versus Matrix, and yes, I have installed and used both.
The Matrix is difficult to setup on a v1.1 box. It took quite a while before I actually got it to work, and the flashing lights were no help at all. With the matrix you are "guessing" about where it is in relation to the d0 point. I feel a lot better just being able to solder on the point and know that I have it right, and it won't come off easily. Also, the alignment holes on the Matrix on my chip were a little off and that was major frustrating.
I also have a friend who "had" a Matrix, but his screw pop out (stripped the hole) after a month of use. Needless to say, he just ordered an X2.
The soft IGR of X2 is a lot better than the hard reset that is supported via EvoX.
The X2 is cheaper...
--Raz.