The title "When you're desperate enough for a 2:45 that you'll pay $250 for a pair of shoes purported to make you 4% faster, even though you are highly skeptical..." was a bit too lengthy.
The short version: I'm not convinced these shoes will help you race faster, but I am also not convinced that they won't.
Most runners have heard about the Nike Vaporfly 4% shoe by now. I'm not going to include any details about the shoe's development, history, and supposed benefits, but you can read about those here, here, and here. I'm going to write about my personal experience with the shoe, which I see as somewhat ironic because I work in a field where we always rely on research-based evidence above personal anecdotes. But many people have asked what I think of them, so here is my opinion!
I purchased the shoes at the beginning of January, mainly because my 2:47 at CIM had me salivating for more and I'd known a handful of people who'd smashed already fast marathon PRs wearing Vaporfys in 2017 fall marathons. Although the shoes arrived about 10 days before the Houston Marathon, I wasn't bold enough to run the marathon in shoes I hadn't worn on a long long run and in a shorter race, but as it turned out I'd have needed way more than 4% in Houston anyhow! I tried them out on a 2 mile tempo shortly after Houston, mostly because I wanted to test them while they were still within the return window, and I while ran faster than I expected to that day, I felt like there were too many variables at play to really judge much (the main one being that I was rested, a rare commodity in marathon training, since I'd taken time off/easy after Houston).
Since then I have raced four times in them, at the Big 12 12K, the Easter Sun Run 6.5 mile 10K, the Rock the Parkway Half Marathon, and the Illinois Half Marathon. I wore them for a 5 mile tempo run and a split tempo workout prior to racing in them, and later in a 20 mile workout to ensure that my feet felt okay in them for longer distances. I've done all of my other workouts and long runs in my "typical" training shoes, which are Hoka Cliftons.
What everyone wants to know first is do they make you faster? Because we all want to run faster! I even did the math before I purchased them...would a 4% increase get me from 2:47:14 to 2:45:00? It turns out that mathematically I need a 1.5% improvement for about a 2:44:44 finishing time...sign me up for even half of the 4%! So far, I don't think they actually make me any faster. Whomp whomp! The workouts I've done wearing them weren't any better than those I ran in my usual shoes. I had one workout twice within a few weeks - 4 x 1 mile split tempos - so once I wore my Vaporflys and the other time I wore my Cliftons. My splits for those two workouts were very close (neither were stellar), with the workout in the Vaporflys being a tad slower. The workouts and long runs I've nailed have seemed more related to other factors, particularly the weather and feeling a bit more rested.
But, do they reduce fatigue? I think they reduce leg fatigue, which in a marathon could certainly translate into faster finishing times. Since I've only raced distances up to half marathons in them, I can't yet speak to how they influence my marathon performance...ask me again mid-June! I have noticed that I've recovered quickly after runs in them, but I also can't say for sure if that is the shoes or the fact that I've been running higher mileage recently. Racing 13.1 is going to take more out of you when you're used to running 50 mpw than when you're used to running 70 mpw.
How do they feel? They feel much different than Hoka Cliftons and Saucony Kinvaras that I otherwise run in, which should come as no surprise because the heel to toe drops are very different, with my usual shoes being low drop and the Vaporflys having a high drop. The Vaporflys feel stiff yet soft, and springly. Their feel does make you think you'll be faster in them! We all know that thinking is half the battle, so... The first few times I ran in them my feet got slightly sore on the bottoms, I imagine because they are used to cushy Hokas, but since then I haven't had that issue again.
I am planning to race Grandma's Marathon in them next month, so I'll further evaluate them afterwards. When you're whittling down your times, every little factor helps, so I figure why not try. It's the same reason I'll wear a sports bra that doesn't rub, socks that don't blister, and (if it's sunny) sunglasses that eliminate squinting - every little bit helps. At the same time, you can find me focusing daily on the other big and little factors: my training (first and foremost!), core work, strength work, foam rolling, sleep, nutrition, heat acclimation, etc. Even if a shoe does help, it can only help so much, and putting in the daily work is far more important.