I'm in no way an expert in nutrition, have only a couple of basic notions. BUT I must say that eating only in a time frame as limited as that will probably be best suited to people that have the time and patience to do it and do not have a very active life.
Follow this: you wake up in the morning, feel like running (sod the "i'm bulking so i can't run" BS) and go for jog. After that, are you not gonna feel hungry?
What about in the afternoon? Before exercising you should charge on protein, afterwards on both protein and some carbs... if the diet specifies there is no limits, there is a chance you may end up choosing incorrectly isn't there?
Usually after that I have MA practice. Though light to moderate intensity, it can go up to 90 minutes of weapon swinging. So my "feeding window" may close during practice. What will my body feast on after practice? Exclusively fat? Sorry, I just can't believe it.
I tend to believe some of the important things my body tells me: if someone is giving me a armlock and it's hurting like hell, maybe I should quit; I go running in the sun and start seeing some white flashes and hearing all wrong, maybe I should stop; I feel really hungry and the stomach hurts, I'm already way past snack time and will probably over-compensate the next meal...
Once again, I admit I'm no expert. But I'm interested in nutrition. One of the things I've read time and time again, both in mags and recent books and sites, is that one should eat more often good meals (correct amounts of determined foods in accordance with the time of day and energetic needs). This idea is preached by bodybuilders, athletes, martial artists and all kinds of sports people. Somehow I feel inclined to believe it. I for one can't imagine a Ronaldinho or a Pramuk or a Federer following such a diet...
Just my 10 cents