My guild cleared Scum and Villany on SM in basically 63 gear on all, with a few 61 pieces mixed in on a few toons here and there. Our tanks were at about 32-33K hp. After that run and with everyone running the new FP's, we have everyone in a mix of 63 and 69 gear and we are blasting through SM with ease. The focus seems to be much more about mechanics in this new op then shear use of gear to overpower the content, which I personally enjoy.
I cannot argue, that in just about any fight that is not a pure Tank'n'Spank "DPS Race" --- Skill > Gear
almost every time. Mechanics heavy fights, and fights that require a lot of team coordination and situational awareness are far more dependent on the person at the keyboard moreso than the gear score of the character.
That said.... I could be wrong, but I am fairly certain that a level 55 tank in "basically 63 gear" is not going to have 32-33k HP, unless maybe they are stacked for endurance with letter-mods and fortitude augments? in which case, that is even more sacrificed mitigation on an already reduced return rate in the 2.0 world. Like I said, I could be wrong, but I am fairly certain that level 55 tanks aren't hitting 33k in 63s.