I've got a 'lite' coating that's rated for 1 year. I use pure shampoo and Autofoam only on the paint, no toppers etc etc. The coating is still going strong 16 months on.
Thanks for the feedback, it's given me something to ponder over... BH Autofoam is meant to be more alkaline with a PH of 12, so I agree it should be okay. I just don't want to wear down the coating, but hopefully it's a non-issue.