This sucks for SinTanks, but I still have my mitigation up to 43%, and ya know, you'd be surprised about how many "white" hits there are in pvp. My shield and defenses are going off constantly because most people are idiots or can't manage their resources properly.
Not to mention I'm fully immune to force and tech for 5 sec with a 45 sec cool down.
I used to share that impression as well, but after watching 31-pt Shadow/Assassin tanks in PVP, their survivability is excellent. The channeled interruptable heal is excellent in smaller scale combat, along with the heal proc from the tank stance.
Resilence rocks, and you also have Deflection.