As far as articulation goes, my opinion is that any more than 60 degrees will hurt you on the rocks more than it will help.

90 degrees of articulation is just ridiculous and not needed.

W/ 90 degrees of articulation your rig will be forced so out of balance so badly that it will actually flip due to weight transfer as the one wheel rises so high and the other falls.

It's the pendulum effect.

It will also cause you to get hung up on terrain that you would easily cross if you limited the articulation.

When you limit the articulation you are bringing other forces into play such as your rigs over all balance, your center of gravity, weight placement, etc.

The biggest advantage is that your crawler will be more stable and easier to drive .