This is your best option. Defense has a much smoother DR curve than either Absorb or Shield (I believe this is because Abs and Shield are higher percent value; they need a harsher DR curve to make up for the comparative improvements). Even accounting for the natural overkill in Shield, you're still better off dumping more Defense than you are trying to get more Absorb to justify it; there just aren't the native bonuses to the values in spec to make it effective.
Thanks Kitru. This is what i was thinking, but i have been hearing a lot of hate about the proc absorb relics so was not sure. I appreciate the answer.