I use only nylon brushes in my bays. I also use them on my broomsticks to hand wash vehicles for our detail shop. If they're good enough on the nicest vehicles going through our detail shop then they're good enough for the car wash customers.
The nylon wears much better and has a much better value. your toothbrush is plastic bristled right? I think the whole hog's hair brush thing is way overrated and I think it's some thing only the car wash owners care about. My customers wash anything and everything with that foamy brush And there's no way I will spend a premium price on an animal hair brush only to see it abused by customers. I like to keep my stress level lower than that.
When I wash my Yukon I use the Nylon brushes. Much less muscle power used to scrub the vehicle down.