A jugg as a tank is the most overpowered class/spec in the game. No, the OP king is not the bubble sorc, and no, it's not a smasher (neither is really OP, just needs some tweaks). It's a tank jugg. No team has any success without a juggernaut tank. PT tank is a total LOL in PvP, and tanksins have different priorities than actual tanking.
So go ahead, and move away from the most overpowered spec in the game.
I am going to disagree with you there. Smash monkeys and their dual-wielding equivalents have become an absolute bane especially since it is now the spec of choice in premades. You put 2-3 of these bastards in one place it's over and even in a very rare 1v1 situation they can easily demolish anything they are up against other than each other within the span of their powerful defensive cooldowns.
The tank spec on the other hand takes a bit more paying attention to play effectively now in that you need to watch to make sure you have the agro. It's a little tougher to hold single target agro but stacking damage does the trick and when all else fails you have your taunts. As far as durability being inferior to the hybrid I am not sure that it really matters with a semi-competent healer. I haven't gone farther than HM FPs and SM Ops on my guardian which I recently respecced back to Defense but I am very happy with his PVE tanking ability, more so than in the hybrid spec. You couldn't pay me to take a tank other than a shadow into PVP, however.