I too am a diehard stam stacker, but that's mostly because I MT a fair bit. So I'd say it depends on what your role is going to be in BT/Hyjal. If you mostly OT/threat/aoe tank then stamina is probably less important than threat or block value.
Also, remember that effective health isn't just about your hitpoints, but also mitigation (armor and block value) and avoidance. Reducing your incoming damage becomes more beneficial once you have enough health to survive a boss's burst damage.
Threat is also important and only 200 spell damage seems a bit low to me with your dpsers gaining more and more damage. There's no point in having 16.5k HP if the boss won't stay targetting you
I'm not in BT/Hyjal, and if I was I don't think anyone can really give you an exact number of health to aim for; in the end it all comes down to what feels right for you after you get some experience with a boss. If you like seeing huge HP numbers then I don't think there's any faults to doing it provided you aren't completely gimping yourself in another aspect.
I highly suggest reading Joanadark's post "
The Point of No More Stam".
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(not always accurate, I spec holy for arena)