Visitors pay for their bandwidth? Since when? Even my gigabit uplinks are a flat month fee.
I have it in place in my firefox browser but it's not turned on. I spend too much time in support forums helping out and have to review sites too much for me to turn it on normally. Plus heck I click on them on occasion.
I know with
WP and
WPMu's Who see's adverts plugins, one of the suggestions is to not display adverts to firefox users. This is suggested as those users are going to be the ones who have an adblocker in place.