So I decided to give worms a try; my boar Tanuki has always been a solid tank, but what's all this noise about the new burrowing ability?
After some camping I managed to tame an Oozeworm, renamed it Dune, and 2 random heroics later it was up to lvl 80.
Took it into SH, and ... WOW. Just, wow.
It took a bit of fiddling with macros and timing to get it down, but dayam can the new pet AOE.

Has anyone else tried using one of these since 4.0? If not, I'd recommend them - before they get nerfed. Because the last time a tenacity pet stood out this much was back when TS was boosted... and gorillas were still the only pet to have it.