As someone who bought the shoes for the sole purpose of finding out if they work. Of course, I am 46 so Its not likely that I am going to get any faster. I have raced in various racing flats through out the past 30 years or so. Last September in a pair of Hoka Tracers, which are just foam and stretchy upper material, I ran my over-forty 5k PR (16:22). In a pair of next% I ran 16:19 on the same course in March. My build up was similar. This improvement is 0.3%, far from the supposed 4+ percent. And yes the shoes are meant for longer distances....but many are claiming Cheptegei 's and Kipruto's road records at 5K/10K to be a result of the shoes. So shouldn't they have helped me more than 0.3%? Maybe they do take the stress off the legs for longer distances, but you still have to move your legs that fast.
Personally, I have had hamstring issues as of late, which I think may be a result of the those shoes. They definitely don't work for everyone.
People are giving the shoes too much hype.