My first guess is that the foam brush will clean much better that the mitter they put on. Talked to a tunnell operator just a few days ago who uses a top brush instead of a mitter and asked him if he had damage issues with it, and he said no. Whwn you got bugs on the front a mitter just won't get it.
I might be wrong, but I think the original poster is talking about converting the side wheels to foam instead of cloth. As far as I know, the Autec only comes with a cloth mitter for the top and does not have an option for a top foam wheel.
Any IBA friction is probably safer with foam rather than cloth. The closed cell material is better for a situation where you might not have as much or any high or medium pressure water prep/flush on surface of the vehicle to remove the loose grit from the finish.
Also, a location that is unattended or only partially attended will not have regular visual inspection and again, closed cell is a safer option for maintaining a cleaner material.