As for PFt8gAwv55fqA8xwPAEfasgVepzQaGAB6m, I'm not entirely sure it's a pool, the address transactions don't look like your typical pool. It could be a big "solo" miner / farm, if so, it's probably a sight to see (or an ASIC...)
O wow I just realized something! I saw your post and remembered I had seen a site like it posted on reddit. When I saw your post I went back and found that site, thats the site (well your site lol) where I got the stats I posted to, I was going to include that link in my post but got distracted and forgot to include it, giving you advice from and on your site lol!. Anyways If its a wallet address I think its on a p2pool thats private or maybe only a group of people know about (would be awesome if that was a group of dispensaries ) or possible one massive whale, someone who has been in the game along time.
~Have a good night