Parallel works fine as long as your servo horn and rudder/elevator horn attachment points are of equal width. It is also important that your horn at the control surface has it's attachment points for the cable in line with the hinge line. I hope that makes sence. If not, let me know and I will try and post o picture of what I mean.

I have heard of crossing the lines and I have tried it on one plane but didn't notice that it was better or worse... so I left it that way. All my other planes are running the parallel setup.