Thank you, Vene, for posting what I was thinking and proving to my brain that I wasn't wrong.
Here's my take:
When I logged on last night just about my whole guild was in BRD doing the Brewfest quest and picking up trinkets or, in some cases, mounts. I'm not a big holiday person, so I told them I'd just run some dailies while they were doing it. After a while (when I realized I wasn't going to get to do the daily heroic with guildies until they were done anyway), I conceded and went along.
We were able to fight the guy four times, and two stamina trinkets dropped. I grabbed one and our former RL roommate Tassh grabbed the other for his Warrior.
If you armory me right now you'll see that I'm currently wearing that stamina trinket. Will I continue to wear it as part of my "normal" tanking set? No. Will I keep it in my bags? Yes.
My other stamina trinket option is the Black Heart. I will lose 440 health if I run with the Black Heart rather than the Mug. However, the Aegis proc on the Black Heart is incredible...really incredible. It happens a lot and is a significant increase in armor during the duration. Plus, you get a cool little crown over your head (Warriors don't have a lot in the way of animations aside from Shockwave and Devastate, so crap like that makes me happy).
Most tanks who are ready to jump into heroics or raiding have at least 25K or so health (ballparking...willing to be wrong...don't flame me). If you've been heroicing or raiding for a while you're likely over 30K. What am I getting at? 400 health is, to borrow a term from my day job, immaterial. The armor proc from the BH, on the other hand, is material.
Should you ditch the Mug entirely? No. Should you be less stubborn than me and take advantage of the holiday to get what really is, all things considered, a pretty good trinket? Yes. Run it until you get it if you have the time because, if you're in a fight where having a dodge or other avoidance trinket isn't going to do you any good and you need raw effective health, stacking the Mug and the BH will, together, hand you almost 3K health and a nice, reliable armor proc.
Regardless of all of that, having a lot of trinkets to play with is always a good thing. I'm very hesitant to get rid of trinkets and I'll usually roll on them if I have the chance and nobody else needs them more (i.e. the Repelling Charge, which doesn't help me now but, if I need to build a resistance set, will come in handy). They're quick and easy ways to tweak your stats to prepare for a given boss fight.
I really need to stop being so hard on the holiday events. Live a little, Mis...live a little.
Happy Brewfest, boys and girls.