Vibram FiveFingers for running.

There are a lot of "barefoot zealots" out there.

When you're looking at shoe design there are two main aspects that play in to this debate; heel/ toe drop and stack height. Vibrams have a zero drop and minimal stack height, so provide negligible protection. Altras have zero drop but a significant stack height so quite a lot of cushioning.

Personally as an ultra runner I prefer a low drop 4mm with a moderate stack height, and for trails a well developed tread. I run exclusively in Inov-8; Race Ultra, Trail Talon, MudClaw, TrailRoc and RoadClaw depending on the terrain.

The benefit of a low drop for me is good ground feel, but the drawback is much more stress on the achilles. The latter point is one that I have to be cautious of, particularly if I'm doing a lot of climbing as well.

Vibrams can encourage a forefoot strike, which can be helpful for some people. I have seen studies that suggest the enforced change in footstrike can lead to different injury risk, rather than reduced risk.

There is no one correct answer, it's very much down to your gait and running preferences. Personally they're not for me, and they're not the magic bullet that the fanbois would suggest.

There was actually a study a few years ago (which I can't find now) that showed no performance difference between wearing trainers, or going barefoot (or using minimalist shoes). So it's a preference thing. My personal experience was I got less injury related problems using Vibrams five fingers. However I could also have just improved my technique as a result of shorter stride length and the elimination heel striking. I like the Five Fingers for comfort, useful for wearing in the water too, e.g. when kayaking. Less constricting than a conventional shoe I think.

I am a fan of minimalist shoes and vibrams. The problem was never with the shoes or the barefoot movement, but with people's misinformed application. Even for someone with strong feet who has spent a lot of time barefoot, there was still a significant adjustment period. Double or triple that for those who never spent any time barefoot. But people are dumb and want to rush everything and cause themselves injuries.
My personal experience was that I was up to 10 miles comfortably running in virbrams. And would still be, except for the trails I like to run on are just a little too rocky, a little too muddy, so I use low or zero drop trail shoes. I'll still take the vibrams out for a 5k or something on pavement or packed trail. I could never go back to conventional running shoes again. They feel horrible to me now.

I have a pair, and I like them, but only for very specific terrain/runs. They could never be an "only" shoe for me.

Whether or not they work for you is pretty much impossible for us to say. The lack of traditional support is something to consider, but so protection from terrain. Not to mention overall fit and the other considerations that go into any shoe purchase.

I am a huge fan of minimal shoes. I don't believe they'll cure cancer and create world peace, but I do think they're better for me personally. However, I know people who run in very cushiony shoes (like your Kayanos) and are very happy, who would be writhing in pain if they ran in my flimsy Merrells. On the other hand, I doubt I could run 15ft in Kayanos without my knee exploding in pain.

The point is, try it if you want, but don't feel pressured. And for the love of your feet, if you do decide you like it, go SLOOOOOOOOOOOOOOOOOOOOWLY to start. As in, run your normal mileage in the Kayanos and then run 1/4 mile in minimal shoes. Every week add 1/4 mile to the minimal shoe runs, and if your calves are screaming, back off and run even less. Walk around in them too. The change from Kayanos to Vibrams would be like going from a cushy mattress to sleeping on the floor. You can adjust, but you're not going to sleep well immediately. In this case, it's the same issue plus risk of blowing out your achilles or snapping a tiny bone in your feet.