Fasted workouts are something of a controversial subject where there is information that backs it up and doesn't at the same time.
Personally, I don't like long duration low-intensity workouts, you can just as much of an effect with high-intensity, shorter duration workouts. Interval training such as HIIT can have as much, if not more of an effect on fat loss, due to it's post exercise effect on heart rate and oxygen consumption. Make the most of your time by working hard! On recovery days, then you can do your low-intensity work to give your body and muscles something different...
Low intensity and high intensity exercise both burn calories, but they definitely burn calories differently... low intensity, my body is mostly running on fat, but at high intensity the fuel of choice becomes carbs. Fat, while plentiful, can't be metabolized into energy quickly enough to keep up with demand at high intensity. Glycogen is a more limited fuel source, but is more easily converted to energy.
VO2max testing (I've done it) is interesting.. the RER (respiratory exchange ratio) actually indicates what fuel mix you are burning at what intensity. But is one workout type better than the other at helping you drop body fat? I do both, as you suggest, because I have the time and enthusiasm to spend about 10-15 hours a week working out. My girlfirends, though, mostly do those high intensity quickie workouts... and still struggle with weight. Maybe quick but fasted workouts is the way to go for them?
My theory is that burning up your carbs (muscle glycogen) causes blood sugar to drop and makes you hungry, so you wind up eating to replace the carbs. Very necessary, too, if you're planning on doing another effective workout the next or same day. Even if you're on a strict diet, I bet your body gets more efficient with the calories when you're going hungry (better absoption in the intestines, maybe less heat waste). On the other hand, I don't think my body tends to 'miss' the fat quite as much; once it's gone, it's gone. It's not like I feel constantly hungry just because I'm thin, or that I don't feel hungry ever if I'm carrying extra fat.
That's kind of why I was thinking that a fasted workout might be worth adding in to accelerate my fat loss... get to that fat-burning place right away, save the glycogen for my regular workout later in the day. Worth a try, I guess!
