I Just got done tanking on my dk in the ptr, and yes the dps might not be correctly tuned with lvl 80 heroics but with the current rune system it is a frantic spam of abilities to even hold even the tiniest bit of threat, with no time to use a Cd even if i had the rune resource to use it in the first place.
The issues im currently having are
1: the cd on d+d is way too long, good that its only one Unholy rune but when you end up using d+d on one pack and the 2nd gets face pulled by dps you cant do jack about it except hope that you have a blood/death rune for a blood boil or some cd to get a blood rune.
2: the rune system is far too clunky, using a basic rotation i have BBFFUU, use one u for d+d, It then ps then spread the deseases, so i have a B and F left for the next 8 sec and the dps are quickly catching up to me on threat or have passed it already, i use blood boil and hope that keeps me above threat but then i have a floating frost rune for 5s by this point the dps have pulled off me and other than taunting a mob back i can hold it for about the 4 s taunt lasts...and then only then ill have a rune back to do something and still nothing for AOE threat.
3: The rune empowerment system sucks to tank RNG to get a rune strike, then 30% RNG on that rune strike to get a RNG depleted rune and you have to hope its right one, now you ask "But you can use death coil". true we can use death coil and dont have to rely on RNG but dose a 2k deathcoil (4k in total threat) hold off the threat say a 8k frostbolt?
If im deadly wrong tell me, but as it stands at the moment