What damage exactly? If someone downloads one of your sets it does not mean you have lost money. If 2000 people download your photos it does not mean you have lost the income from 2000 potential subscribers. A download does not equal a lost sale!
In the vast majority of cases you won't have lost any money at all, in fact you'll have attracted many more potential subscribers, as long as your content is of sufficient quality or fills a missing niche.
I'd actually suggest you experiment and shoot a set that you'll solely release on P2P via torrent sites. Release it (anonymously) and I gaurantee you'll see an increase in site visitors and completed subscribers. Go a stage further and do some A/B testing, using a different url watermark on the photos so you can track visitors coming directly from typing in the url they see.
I'm not being greedy at all. I'm not trying to make money from anyone here under the guise of combating piracy. I subscribe to pay sites.
All I'm trying to explain is that if you want to combat piracy, great. If you want to root out the causes of piracy and act on the torrent sharing sites then that is admirable. Extorting money out of people is wrong.
You have to get out of the mindset that just because someone downloaded something it means you've lost money. Whether the file was there or not, if they wanted to subscribe they would have.