OK so my CMB would normally be... 4 (Base attack) + 0 (str) + +4
and my own CMD be.. 10 + 12 defense + 0 +5 dex = 27
Now Since I'm using a trip power I presume I would replace my Melee attack and Str with the trip power's Ranged attack and Rank, making it a +10(Attack)+10(Rank)+2(Feat)=+22 trip check CMB. Due to Improved Throw the opponent would only get the lower of their STR or DEX instead of adding both.
So trying to trip myself I'd have CMB 22 vs CMD 22, meaning it's a straight dice roll. Is that accurate?
Or is the CMD a DC rather than an opposed check?