I leveled prot as well and I agree with the above comment that it's only hard until you get consecrate. I will say that dungeons DO go faster if you are ret and are somewhat skilled, AS LONG AS YOU HAVE TANKY GEAR. Seriously. If you want to queue as a tank, ever, make sure you're saving the tankiest gear you can right from the get-go, and always have the best shield you can find and afford because it makes a difference. Sure, you *can* tank Deadmines with a 2-hander, but it's going to go slower and I will be silently hating your guts.

Also, I would not stay ret past the point where you would pick up Avenger's Shield (I don't remember what level off the top of my head anymore, since I don't really pay attention that closely to when I get stuff, just that I got them). I have run with amazing ret Pallies in BRD (wearing tank gear), so it's doable up to that level or so. But please, unless you're running with good healers or are exceptionally skilled, err on the side of caution and level prot- the AOE grinding between dungeons (yes even tanks have a *little* wait time) can be awesome.