Your spec is fine. It is a threat spec vs a maximum damage reduction spec. Honestly I am going to go to a similar spec whenever I can be bothered to find a warrior trainer. For the content you are doing, your are geared plenty where threat becomes more important than survivability. Until you find yourself having difficulty surviving in your current guilds content, stick with the threat spec.
Those 2 points in Imp Demo shout reduce physical damage inc to you by something like 1-1.5% -- there are only a couple boss fights where Imp Def Stance over those two points makes more sense... unless you have someone else to do Imp Demo or Imp CoWeakness.
The beast is getting hungrier.