Boston Buildup Serie 2012 & Efficiency

I took part in the Boston Buildup Series 2012 this year. It's a great series put on throughout the winter aimed at buildup for a spring marathon. I just ran them for fun. I posted a PR in (almost) every distance of the series: 15, 20, & 25k. I didn't run the 10k. After running the Amica marathon in Newport, RI in the October 2011, I really started to break in to my Newton Distance. I never did follow a training plan, but at some point in the early winter, I found my stride. My overall speed had increased dramatically compared to a year ago. By march 2012, I had shaved 6 minutes off of my previous years half marathon PR. also to note, that PR was a 13.1 mile split running in a 25k (15.6mi) race! So, I believe my overall time could have been slightly faster. I also chewed 38 sec/mile on a self timed 5k. I had increases across the board in all distances. I  attribute my speed not to strength training, speed work, or running volume. But to something I feel is overlooked in running. Efficiency. in the case of running, efficiency translates INTO speed. Only because you are using much LESS effort to run from point A to point B. With an efficient form, you can run the first half of your long distance race expelling much less energy you used in previous races where your form may not have been so great. Then kill it on the second half. I accredit this to my Newtons. Although they did NOT make me faster. They DID enable me to become more efficient. Therefore I became faster as a result. The forefoot lugs on Newton running shoes almost force you to land on your mid foot- forefoot while running. Obviously you could still go out in a pair of Newtons and run with a heel strike! But you are less encouraged to do so. Immediately you will notice a difference. And I feel if I continue to work on speed, coupled with some hardcore strength training, I will only get faster. I can't recommend Newton running shoes to everyone. Because I have read (and learned) that not everybody wants to change their stride, and won't feel comfortable transitioning. Below are my 'unofficial' garmin times.
Norwalk 25k
Farifield 20k 
Ridgefield 10k

An excellent video demonstrating natural running in a few simple steps.
http://www.youtube.com/watch?feature=endscreen&v=rTMzdRhsPrA&NR=1