I will say that running on your forefoot can take 10 seconds off of your 1500/mile time. It is a great practice because it is much more effeceint stride. As the race gets longer/pace gets slower you'll likely notice that you'll initially strike the ground with your forefoot and then your heel may tap the ground very briefly. I know people that will run 3k/5k races on their toes for the entire race. My HS coach talked about a girl who trained with him at UALR that would run 8k/10k races on her toes for 75% of the race.
You're absolutely right, though I don't know about ten seconds a mile. I do all my running in racing flats (part of the advantages of being 125 lbs) and when I'm running on pavement at a good hard pace, I find that I land on the balls of my feet and spring off the ground. Of course, as you run faster or when you're tired, your form will deteriorate.