Kieth,I'm not informed enough to go into a detailed explanation of the geometry changes. Lowering the front significantly, changes the rake, shifts weight to the front thus lightening up the rear, in general it upsets the balance of the bike.
The effects, turn in is usually quicker, but overall stability suffers, brake dive is increased which unloads the rear even more under braking. That said, minor adjustments are possible, and can improve handling in some instances. I've moved the tubes up slightly on DS bikes myself for tuning purposes. But lowering just the front by a significant amount is simply not a good idea.
