I've perused various forums/guides and most seem to suggest get hit/exp before focusing on purely tanking stats. I personally don't see the point of this (yet). I'm currently just doing heroics. I haven't had any issues with threat. Is threat that big an issue once you get into raids that hit and expertise become so important?
It's a subtle change from pre-MoP tanking, where hit/expertise were secondary to some tanks, since getting Rage from being hit resulted in more attacks being available and more threat. (Cata Bears were one of the outliers, since critical hits proc'd our then-Savage Defense bubble, so it was fairly important to hit early and often.)
The key point is that you only get Rage when you hit stuff now (and nothing when you get hit), so those misses/parries/dodges represent lost Rage income and lost Active Mitigation button presses. And while you could go for passive defense stats (including stam stacking), that's not going to fly long term raidwise, because the healers have had their mana pools hardcapped on the other side of the equation, so they won't be able to 'heal through it' either.
If you're just going to do LFRs, though, I wouldn't sweat it too much. Only Lei Shen and the trash right before his room really hits hard enough to stomp a tank in LFRs, and then only if the healers are preoccupied or hugging the floor.