I like berserker a lot more now that almost everything is AOE. . . but guard shouldn't feel squishy, especially if you are in such good gear. . .I think the issue w/guard is that the defensive abilities have such short durations compared to say, berserker. You really have to get used to timing things. Use right side prestige for guard imho as well, with hunker down, your group temp buff, and the right side prestige going you have pretty good damage reduction rolling almost constantly.
I almost always dual weilded on my guard, but have a tower of stone+shield macro obviously (i'm sure you have this already, lol).
But I think say, compared to berserker or whatnot, you are going to feel squishy vs large groups of mobs, just the way it is, stoneskins will get blown through way too fast. If the next expansion has a lot more single target hard hitting fights it might be worth it to go guard again, or if they massively boost guardian single target DPS, but right now it doesn't seem worth it to me with the tweaks berserkers have received.