We are a hardcore raiding guild ( X-Raided ) who have downed Dreadtooth on 4 stacks, but not easily and nor is "farm" status anywhere near BUT not do to our incompetence, let me list the reasons why.....
1. Sector X population - with such a high number of people in an instance we have 2 maybe out of 16 who don't have lag
2. Griefing - constant constant constant random flow of people who grief our group with a pull that gives us the debuff causing us to wait yet again for the debuffs to drop for a pull
3. P.A.T. - Do to the positioning it is ideal to have Dreadtooth in we find it necessary to allow Dreadtooth to pat to few key locations before a pull
4. Aggro - The aggro table on dreadtooth gets lost tons, not talking about during "Sonic" either where he is supposed to drop aggro, talking about on pull....we wait for 10-15 secs even to let tank build aggro and pffft, somehow pull aggro off tank and wipe raid. This also happens alot during fight outside of "sonic" ability, even though we have multiple tanks ready to taunt back it does not work because he takes 3-5 secs to respond to taunt (long enough to wipe the raid)
OK Bioware if you would like to come with me on our raid night dedicated to this horrible WB you would see that dealing with these listed problems means we get 1-2 pulls in a hour.....is that what you intended? We started having fun at first simply because it was new, but now the fun is gone. At the end of our raid night for Dreadtooth everyone pretty much is in a bad mood from dealing with all the problems around this fight, the sense of accomplishment is diminished by the state of your area therefore lowering our need to accomplish it......
So BioWare I ask you.....Dreadtooth - Why should we even try?
Well, #4 sounds like you just have jugg tanks or something. The other two types won't lose aggro very frequently. Jugg tanks probably need another threat buff. One thing they can do, though is get an on-use power relic and pop it at the beginning of the fight, then on cooldown anytime they're main-tanking (and yes, I know that's not ideal).
Edit: what I'm saying is threat loss isn't really a problematic boss mechanic. It's a problematic class mechanic.