Don't underestimate the mitigation that comes from Rooted's regen bonus, especially when Earth's Embrace is active. I put 2500 or so hours on a Stone/EM tank back in the old days, and re-rolled him as Stone/Spines on Homecoming. The only time I turn on Granite is for major AV fights, or things like the Nictus ambush in the ITF. The rest of the time, having almost 3400 HP and regenerating 70 or so every second, combined with Rock Armor/Stoneskin/Fighting pool, is enough.
I don't bother with Brimstone or Crystal at all - but I slot the heck out of Rooted and EE, and built for perma-H