It's on a per torrent basis, there is no specific tracker used by this site anymore.
If the person creating the torrent adds trackers, then those will be used by everyone. Adding trackers manually afterwards in your client doesn't help in the slightest unless other people do the same thing on the same torrent. I never understood why people actually do that.
If it has trackers, then you will be able to seed no problem with your seedbox. People don't need to choose between DHT or trackers, DHT is simply an extra way of connecting to other people.
And if you don't have the file yet, then if someones downloads it via DHT, he will show up on the trackers as a seeder(and as a leecher before) if he doesn't close it and you'll be able to download it.
Basically, if the torrent isn't dead and already has trackers in it, you're fine.