My son is just finishing up his first year of cross-country in high school. Out of ignorance on my part, he has done all his training in Nike Free 3.0's, which I now realize is in the minimalist camp of shoes. He races in racing flats. He hasn't had any injuries apart from some minor calf soreness late in the season. He likes the shoes because they are light and flexible.
Once the season is over, he will start base training. Are these shoes safe for putting in mileage? Is my son now acclimated to minimalist shoes, even if by accident?
The best way to tell if he is good for minimalist running shoes is to judge his running form. If he strikes the ground first with his midfood or the front of his foot instead of his heel, then he should stay with minimalist running shoes.
That's all it boils down to really. A minimalist shoe has the same amount of padding in the middle and front of the foot as a regular trainer does. The difference is there is typically 8mm more padding on the heel of a regular trainer. I like minimalist running shoes way better, and I do all my training in them now.
It took me a while to get my form down, but I increased my stride rate, and hold better posture during the run so I don't slam my heel first. Some runners who are minimalist runners still heel strike first, but they have a slight knee bend, and land over the center of their gravity, so it minimizes the impact on their legs.
Just watch your son running and see if he has a good stride. I wouldn't switch back from minimalist running shoes ever! He shouldn't either. Just keep focused on good running form and he should be fine.