I hear ya. I'm still probably leaning towards a 26er (650b?) because of the maneuverability on the down. I don't think I'll be taking any chairlifts though.
I agree with Antmav - 29ers aren't true AM bikes - those are two great bikes - my friend had the Pivot - now the Mojo. I personally love my RM Slayer. Remember - All mountain is ALL mountain. DHing an ALL Mountain is fun - especially at Highland! XC guys in lycra do it on there HTs - when you DH - your XC skills change immeasurably! Don't short change yourself.