Nice to see some good tech discussion going on.
The talk of width/scrub reminds me of an
article about Jason Scherer's (KOH King) new build. He traditionally ran zero scrub with deep back spaced wheels like many other racers. However, on his new car he's running positive scrub, with a shallower back spacing. With zero scrub your tire has no swing out. So when he found himself hung up in the rocks, and searching for traction, he wasn't getting the result he was looking for since his tires were pivoting on single points. With positive scrub the tire will swing out and allow it to search for traction better. I know I've found myself hung up, and sawing the wheel trying to find traction.
It's all a compromise, and why we all build our rigs differently.