Your DPS as "mini prot" can be fairly decent - we had a warrior in our raids do that for a while, and he did ok. Nothing earth shattering, but it was certainly viable DPS. Having to keep sunders up shouldn't be too bad as Fury, as long as you do it only a couple second before the stack falls off. Combining that with Demo shout and Commanding shout also shouldn't have too much impact (Fury warriors keep those up in raids quite often).
What I found worked well for learning Fury is to skip out on heroic strike entirely until you get a good feel for what your rage generation is like. Using heroic strike badly is worse than not using it at all.
Whether you need to go prot basically boils down to whether or not your healers can handle you getting crushed. The trash should give you no problems as even a pure DPS spec. I suspect you'll need the extra shield block charges, unfortunately. If you do end up putting points in prot, Tactical Mastery is well worth it. I don't remember the extra threat it adds offhand, but it's something around 250 IIRC. It becomes your Shield Slam.
Could you DPS just as well as prot though? Maybe. I recall doing around 850 DPS on a mag kill as prot (with a WF), and 900 DPS on Anetheron as Fury (without WF). I stack a ton of ArP though, so the difference would probably be closer. Just make sure your threat isn't going to be an issue while you DPS.