CFR from Amtech also do a cleaning agent that leaves a residual protector behind and they are a very reputable company, I don't think they would say it if it was'nt provable.
I think this sort of detergent could be quite a useful marketing tool, every job you could sell as a clean and protect at a higher price.
I've just ordered some detergent that leaves a residual antibacterial coating which in the initial clean will kill 99.9% of all germs and then keeps working after the carpet is dry. I thought it would be a good seller to nursing homes and children's nurseries. I can just keep it at home ready to use when needed. Also it comes with a really professional leaflet that you can download and give to the customer when you quote.