Yes, there are other piracy forums out there that are bigger than the Marcus board...however, unlike these other boards, the Marcus one is genre specific.
On an all-in board, with all the diverse genres and fetishes that are available, I'd be very surprised if IR made up 5% of the cotent...on the Marcus board, it's 100% of what's available.
What gets my goat is that the selfsame people who are bitching about certain girls not popping their on-camera IR are the same ones bleeding IR producers dry and ensuring they can't compete financially when it comes to getting holdout talent to up their levels.
If you equate the thread views on the main piracy topics on the Marcus board with a nominal 50 cent to $1 dollar loss (when in reality it is probably a lot more) then the Marcus forum alone has cost the IR genre hundreds of thousands if not millions in lost revenue.
The other reason the Marcus forum gets the beatdown is because tritone posts there (and fileshares there too), and you know what high regard we all hold him in over here.