I received my HRM and tentatively set out on my first MAF run with a little knowledge gained from the helpful people on this site, and to be honest my feedback would be that I maybe think it is not for me. Not because it is a bad method or anything, but because myself as an individual introduces too many variables for it to be effective.
If you were running on a flat athletics track in a warm location under controlled conditions, with constant heart rate (I.e. as maffetone originally trained his runners) I can see it working well, but it does not translate well to running in the real world.
The basic problem I found is that heart rate is not constant. Running at a constant rate off road and hilly is difficult.
If there is a hill or you have to stop and start say for a gate during the run your heart rate changes. Heart rates in the real world (which has more accelerations, changes in effort due to terrain etc.) result in a much slower pace and a different gait.
Also I live in a country where there could be as much as 10°C change in temperature from morning to evening and I run at all times.
When I went my run today after work, stupidly I had my coffee pick me up prior to it, I guess this may have affected my heart rate too.
Running in different weathers must be a variable too which would affect results. The nice warm, dry summer evenings, opposed to wet slidy Autumnal leaves underfoot must be a negative variable.
I think I need to seek out a program to follow that a recreational runner may use to build base fitness, as this is all I really want and throw it in when I'm out with the dog. The equivalent of a "Simple" program for runners. I thought MAF was it, or am I just not understanding what its function intended results are?