I've actually started tanking everything in my hybrid tank/dps set just to see how it went.

With HQ buttons, in party and defiance on, I sit at 8.1k+ HP, 410 STR, 360 DET. This is without melded jewelry, using mostly i90 DPS Allagan/Primal accessories. I tank T1/T2/T4 (double dreads)/Titan+Ifrit EX and receive no complaints from healers about damage taken.

My DPS has been the following (all with defiance on 100% of the time):

T1 Snake: 200
T2: 170-180+
T4: 150-160+
Primals: 150-170+

With more tweaking to skill/cooldown usage and trying to toggle defiance, I'm sure I could eventually pull 200 DPS on each of those fights... All in all I feel a DPS build for WAR tanking is definitely worth it.