you hav epointed this out very precisely in layman terms, but whats so bad about depleting the glycogen stores?
i realize they never get totaly depleted,or we would just die, but the less of it is around, the better the fatburning will go.
i know, glycogen mustnt be depleted to burn fat,it works both ways.
btw, i bleieve, kinda certain, that on gear, highest as possible intensity cardio is best, under this hormonal enviroment the body doesnt give a shit about proper ratios, the protein is spared anyway, can go full out.
my cardio,if i do it, is epic repeated sprints with small joging breaks, rinse repeat, all the way until i almost gas and pass out 
I think the low intensity cardio is anti-catabolic during a period of calorie deficit. I like to think that by keeping glycogen stores as full as possible, you can minimize muscle loss, and if your diet is just right and you keep cardio moderate lengths and intensity low, you can still burn fat. It's a complete different approach than yours and no ones and OTH's, but it worked for me back when I was competing naturally, and it works even better on gear, like everything does. I was able to get sub5% for my last show when I was a true natty. Of course there was calorie deficit present, but based on what I learned about this from Biochemistry classes, I LIKE and HOPE to think I preserved more muscle in the end. Absolutely the less glycogen present the more fat to be burned, but you're also going to burn amino acids via gluconeogenesis to create energy. There is always a metabolic price to pay for whatever you are doing or eating, that's my theory.
I also like the heart healthy benefits you get from low intensity cardio, and the nutrient partitioning effects. As I said I get a minor pump from it. I can't help but think 20 mins a day is a good thing.
You know who feels even stronger about this is George Farrah! My good buddy has been his client for all of 2012. George has almost every client doing some low intensity cardio because he believes it is anabolic in the long run. He has his super ectomorph clients doing even MORE low intensity.
Ideally I think a mix of low intensity and high intensity on different days is the way to go; get the best of both worlds, because both provide unique benefits. I do low intensity 6 days a week post workout, and high intensity bike ride or running or something one day a week.
