Okay, I checked the book "How To Raise Chickens" by Christine Heinricks, page 104. Basically I think she is talking about the ability to compost and by composting, raising the temperature (due to the natural breakdown of the poop and shavings etc) with the dirt floor. This is great if you need compost. I, on the the other hand, just want a clean, dry and warm coop, and I don't have a dirt floor. After seeing the squaller my hens lived in before I got them (basically no bedding at all) DLM sounded good to me. And still is. The coop is ancient, wood floors, odd windows, etc, but it works and most important, it is as safe as possible. It is clean, dry, and when I get the windows up for the winter, it will be cozy. I hate to say this, but my coop is so user friendly I sometimes take a snooze in it with the girls.
I have at least 6-10" of shavings. I clean up obvious poop every other day, and refresh the shavings when needed. Every time I add new shavings I also add DE. There are almost no flies or any other insects around, and almost no odor. I used to work in a cancer screening lab, and I was the "canary" so to speak, because I have a very good sense of smell, vapors. The coop smells pretty good to me, or I wouldn't nap there, right?
So those of you with wood/concrete floors, I wouldn't worry. The DE and DRYNESS of the coop is the important thing. Also, as an aside, too much of anything is not such a great thing. I have to keep myself from using too much DE. Just my thoughts.