Short answer:

The 12R5.2 is pretty awesome the way it is. There is no value in messing with this.

Longer answer:

Level tubes will put the least average side load on the inside of the tubes as the pod rotates and the tubes slide in any out of each other. This makes them more consistent and last longer between rebuilds.

It really doesn't make a big difference. I mean, you could change the angles and mounting points 1-2mm and the car will go around the track the same.

Performance won't change unless you move both inner and outer mounting points closer to or further away from the center pivot. This would reduce or increase the leverage and travel or sweep of the piston in the tube thereby making the tube provide more or less damping for the same given fluid in the tube. The friction characteristics of the system would also increase the resistance to sudden movement (off roaders call this "pack") as you get further away from the center pivot or vice versa.