I'm curiious on how they get those things to fit all the different toe types. I'm one where the 1st toe after the big toe is longer than the big toe. Some folks have toes that go pretty much straight across. Do they have different styles to accomodate different foot/toe shapes or do you need to use a belt sander??
My second and third toes are both longer than my first. I've been using VFF's for about 3 years. I haven't had a problem with them in any of my VFF's.
My first pair was over-the-ankle neoprene KSO's - not made anymore. Great for cold weather, the most challenging to take on and off. The Flow looks similar, but doesn't go over the ankle.
The next pair was KSO, similar to the type still made. Better for warm weather. The mesh allows a little more debris to get into the shoe, but has never been so much that I've wanted to stop and take them off. Two years old, worn for at least a few miles nearly every day for about 6 months out of the year, and still in good shape.
Scored three more pairs this spring due to great sale prices. Except for the two pairs I've received as gifts, I haven't paid more than $50 for any of them.
Sprints: Similar to the KSO's, but less covering over the top of the foot. Worn twice so far. Both times last week for outings of 5-7 miles each, a mix of running and walking. Cooler still than the KSO's. I did get a few scratches on the top of my feet. I had a bit of discomfort, loosened the straps, and they were fine.
Classics: Got 'em for walking around shoes. They've been fine for dog walks, don't know how they'd be for running.
All of these have very similar soles. Decent traction except on mud, snow, ice, and wet leaves. They're fine on slabby rock and I haven't had a problem on wet rocks either. I prefer these for outings to about 10 miles when I'm carrying no more than a few pounds.
Bikilas: These feel the least barefoot of any of them. Used once for about 6 miles running/walking in the Holyoke range. The sole and insole are a bit thicker which means it isn't as flexible. If I flex my toes in the other models, the toe pockets flex along with my toes. In the Bikilas, my toes flex inside the pockets. I thought the treads might extend the use of VFF's in the conditions where the others might be too slick (i.e. mud). With the thicker soles, ground-feel isn't quite as immediate. Along the trap rock of the Holyoke Range I noticed I was making foot placements in these that I wouldn't have made in the other VFF's, such as stepping down onto pointy rocks. This might extend the range in which I'm willing to wear VFF's. I liked the bit of padding in the covering atop the foot. A couple of times I tangled in brush or a rock rolled over my foot - no scratches in these! I did not like that more debris gets into these. Unlike the others, I stopped twice to take them off to clean them out. Perhaps it's because there's no way to tighten the heel?
Gaiters: I wouldn't use any of the VFF's with anything that needs to strap under the foot.
Adjustment period: I didn't have much of one, but I've always been a forefoot-strike runner. That's mostly how I walk too, if I'm barefoot. It takes 3-4 runs before the calf tightness stops happening when I start wearing these in the spring. They're too slippery for winter trail running in snow. Not a problem this spring - given the lack of snow I wore them nearly all winter.
I almost never get comments on them. People are usually too busy paying attention to Caboodle!