So my life right now with young kids and such doesn't allow for much raiding. I have been really loving the new LFG and getting groups in 3 seconds. I realized I should spec for that since that is what I do. I've made one attempt at it, bumped my dps up 400ish from 1200-1400 to 1800. But I'm finding myself rage starved.
The basic problem I see is you're still losing more threat by not speccing impale than you will gain by going for the stuff in the fury tree.
Honestly I would just use a standard 15/5/51 and change my glyphs up instead if I was going to target 5s specifically, maybe with the exception of picking up improved bloodrage so I'd have more rage to start big pulls.
I don't think glyph of sunder armor is worthwhile for AE threat, though - the amount of threat that the second target gets is negligible. You'd be better off threatwise with glyph of vigilance and vig on the strongest AE dps.
I'm assuming you are tanking, rather being rage starved as fury. Let us know which.
If you are rage staved as a tank, the answer is pull more, provided you can handle it. As a tank, your rage from taking hits is more significant than damage dealt rage.
The other issue is hit/expertise. Expertise is capped at 26, and hit at 263 hit rating. Get your expertise skill up to 26 and then work on your hit rating. A warrior that misses generates very little rage (on your rage bar anyways, your personal rage is a different story).