Dave,
That is a good question. If you believe any/almost all of the physiology research done in the last fifty years or so, then your thoughts are correct. People in general (80-90% of the time) find their own most economical running style/stride length. This means that when you put them on a treadmill and follow O2 uptake, you find that having the person do things that they do not normally and naturally do causes them to use more oxygen at the same speed. In other words, they become less economical. In that sense, there probably is not much sense in messing with your running style in a major way if you have been doing it for any length of time.
(That said, the goal in a race is not to be most economical, but to have the best performance irrespective of economy. In other words, people generally speed up by taking longer strides, which is less economical because it uses more oxygen. However, if it gets you to the finish faster, then it was a good strategy.)
Tim Noakes (physiologist from south africa) published a paper that showed the POSE system does, in fact, cause you to change you stride by placing more load on your calf muscles/achilles and taking some off of your knees. No surprise there, but it is always good which science confirms something you think :^) I guess if someone had recurrent knee injuries, it might be worth a try. By the same token, I'd be nervous about encouraging someone with achilles issues to mess around with this. I get into this stuff a little more in my book.
For what it is worth, though, I don't think it is a very good idea to actively try to run more off the mid and forefoot than happens naturally. As a physician, I see many more injuries in people who run more off the forefoot than I do with people who run more rearward. (Almost everyone heel-strikes some when running. It is normal for most people.)
Philbert
Dr. Philip Skiba
Scientific Training for Endurance Athletes now available on Amazon!