I have two tanks (one 428, one 414) and two observations
1) People are desperate for you all the time (the tanks get their keystones groups filled within seconds. The 414 one, it left me dumbstruck, got a couple of times people with 430, 440 even ievel showing off sometimes, which never occurred for the main and the healer)
2)While trivially difficult levelling, the difficulty of tanking spike immensely in ''serious'' content