Ok so the current 1.5 headtube offers you 3/4" reduction with a zero stack, this is why turner reduced the overall head tube length to accomodate for this:I want (like MANY others) a low front end. 1.5 Allows a lower front end period!!
1.5 offers a 3/4" height rediction with no negatives, it is that simple.
HT Lengths 06: 4.5", 5", 5"
HT Lengths 07 3.7", 4.2", 4.7"
So for both the small and medium (sorry large) you have a .8" stack height savings before your headset ... and a chance to run a lighter CK headset... Granted if they reduced it and kept a 1.5 it would have some killer savings in height, but i think turners main objective with the 07 was to reduce weight, and the geometry changes they made while redesigning the dhr seem pretty spot on