jogge wrote:
What difference if any does higher or lower shoe drop make assuming all else is identical?
.... Does it matter for injury, stress areas, economy, or what? Is there any scientific evidence for it?
Good question. One of the difficulties in testing shoes is that runners adapt quickly to changes in shoes but slowly to become efficient in those changes. I did a test on running efficiency three years ago. The shoes were identical New Balance models that had been modified with different levels of firmness in midsole and heel. The goal was to see if there was a measured difference in efficiency by looking at O2 levels, heart rate, and so on.
The results were mixed, but one unanticipated consequence was that I could feel my foot strike very slightly shifting to accommodate the different levels of cushion.
To address the OP's question, a higher heel to toe drop allows for more cushioning on heel strike which in turn allows runners to heel strike harder. For slow recreational runners, this is an advantage because they can run a little faster by overstriding. The problem is the high heel to toe drop puts a lot of impact force on the heel AND the plantar. Surprisingly, it puts impact force on the arch FASTER than a midfoot strike! The result is the plantar stretches and collapses more, causing the ankle to flex in and the torque to travel up the lower leg bone, resulting in twisting this bone and moving the knee out of its natural flex position. The result can be shin splints and runners knee.
In my own experience, switching to a lower heel to toe drop shoe allowed me to transition to a forefoot strike. This in turn eliminated my chronic runners knee and I became much faster over shorter distance races of 400 and 800m.