DamianJ - Good post.
In my case I am confident that that fighting piracy does keep sales up. But also in my case I am not in a position to state that "X" amount of people joined due to this filelocker going down or that filelocker going down. The main reason is that at the same time I send donations to this project I am also doing other things.
I have a guy in my office 40 hours a week to help with piracy issues.
I do hours a week of work myself on the same issues.
I register my copyrights, file suits, and later use the judgements to discourage others from posting my materials.
I even travel cross-country to stop piracy if thats what it takes (see
http://wp-board.com/ blog).
15 months ago when Oron went down I did see a large increase in sales. Stopping a file locker in that case (not by AK) was good for me looking at monthly averages - just like the WP-Board deal was in 2009.
So, I can't post a firm number here swearing that much more was sold in memberships because of the Stop File Lockers program but I know its one of the things that helps.
Jimmy