I mean, you CAN get to +80% Damage with Shield if you build specifically for it. Assault Hybrid, Assault from Leadership, split up Might of the Tanker into three pairs, gather five 3% bonuses, the 2.5% from five Shield Walls, etc etc. But you're giving up a lot to do that, and you'd still be lacking Rage's +ToHit bonus, which is arguably as good as the +Dam.
I would just take Rage. Yeah, the crash is awkward but it's just ten seconds every two minutes (I don't double stack) and you still Taunt, Handclap, use your Incarnate Judgement power, move around, whatever.