I have done some fairly vague testing of this on our last KZ run and I must say this seems indeed interesting. Will test more tonight and hopefully with some really nice results.
Prot DPS in a raid is quite ok if you wear glass cannon DW gear. Devastate spam adds decent DPS and Executes are better than those from Arms Warriors. It's not good enough for pure DPS races or a pure DPS roll, but that is quite logical.
I fear this might be shitheaped, but I guess something good could come out of this.
Proper gear, (extreme) potion usage and some skill can almost make up for being prot specialized.
One of our MTs has been 2nd on damage meters on an Aran kill, with his 8/5/48 spec.
I got the same result (2nd on damage) with the same spec (8/5/48). I don't think it's a coincidence. First was a fury warrior, maybe Aran just favors warriors. Devastate made up for about 45% of my damage. It is really a huge damage boost for protection spec.