No. Stone tanks do not need it at all unless your getting it for weave. even then, my tank has 50 percent s/l through set bonus's. I would rather use those 3 power picks for more attacks or better slotting.
My stoner has tough. Not needed on granite, but it is a godsend when solo, small teams, when you can actually tank without granite (no -dam, -rech, etc). Rooted still stucks though. I use weave (always) and tough on small teams and solo, but then, you can always do the dual build thing ;-)
50 Tanks: Invul/ss, Fire/ice/fire, Ice/em, Stone/fire
WP/Stone, dark/dark, shld/mace
50 Other: WS, SS/dark/sc brute, BS/Regen/WM scrpr, fire/fire/force blaster, rad/kin corr, mind/rad ctrl, ill/storm cntrl
Just a quick update: I gave my Ice Tanker Tough and Weave. He is nigh untouchable now. Also, my Willpower Tanker has Tough, and his survivability is much better. He takes less damage than he regenerates finally. I think there is hope for my Shield Tanker now. It is harsh to have so little amount of attacks at level 26, but I have to admit, it is worth it. Thanks for the input guys and gals.