to my knowledge (which could be all wrong) clients like utorrent will only resort to dht (if it's
turned on) as a backup - if all else fails. as far as private trackers are concerned, they require
you to turn it off if you're uploading a torrent because they are private, and dht is not! when
you're downloading from a private tracker, it don't matter, 'cause it just won't connect to anyone.
i leave it on all the time, and never have any issues with routers, (linksys is the only one i would
use) private trackers, etc. i do use
"peerblock", and regardless of what you'll hear out there, it's saved my ass on many an occasion.
(i have been shut-down by my isp without it).
as far as download speeds, i can usually download one of these 42 minute tv shows in about 3 and a
half minutes. anyone needing a private tracker service can sign-up with torrentday and get really
good service - plus, they make it easy to maintain a good ratio, unlike some other places
(ilovetorrents, 4 example).
peace!