The numbers aren't tweaked and finalized yet, so it's impossible to tell. Everyone can do a shitload of damage now.
They won't tweak numbers before they at least have a release date on MoP. Just hang in there!
I've played very little on my warrior on the beta (lv 86 or so only) so obviously I have no idea. However, the arms gameplay atm feels amazing. My warrior is (sadly) going to be my alt only in MoP because of raidsetup, but I think arms will be a really fun spec in MoP.
More on topic about the damage, the only hint I can give is people talking about arms being borderline OP in PvP.
Have they added addonsupport on the beta yet? With the raidtesting going on we might be able to get some real numbers instead of me speculating