>Can you share any experience backpacking barefoot or with very minimal soles (other than the 5 fingers)?
Yes. I've used extremely thin sandals (no idea what brand) for a long time before five fingers came around. Even adding a 5mm sole adds significant cushioning for the terrain I go on and I dont' feel limited by them. The biggest limitation with those are the fact that the footbeds are plastic / rubber and when wet are slippery, that the footbeds cannot breath at all and they cause calluses like crazy. For day to day comfort though, they are much more comfortable than the ~1-2mm thick soles on the vibrams.
Don't get me wrong, I think that in a perfectly flat, softer terrain I could adjust with the vibrams, but I don't hike on anything that even approaches that. Adding a pack to that, even a 10 lb one, makes things more tricky. I suppose it could be what makes barefoot running possible though, usually you aren't running when on uneven, rocky terrain.
When I switched to vibrams, I switched my gait to the forefoot first subconsiously, which has been mentioned many times in that article. Yes, your body starts absorbing the shock differently and starting to cushion your steps more than the heel first. My muscles thought it was weird at first, but didn't seem to have a hard time adapting. Instead, I think my weakest point was that my arches and heel were easily too easily injured from uneven terrain and repetitive poundings directly in the arch of the foot when flat footing wasn't possible. River rock was especially dreadful. From the backpacking trip I attempted I actually had visible bruising in the arches from rocks. Given the terrain, it wasn't a matter of trying to step more carefully, scree is scree and it's full of sharp angles and loose rocks. I found that when standing flat footed I often had discomfort on hard surfaces on my heel, but not the forefoot. On soft, flat dirt however, it wasn't a problem and my foot seemed to cope well, but my trails never stayed that way long enough for it to matter.
For now, I'll personally stick to using the vibrams for shorter distances or activites which require more tactile feedback on the feet.
By the way, anyone else had in between the toe blisters from vibrams? I have and I've never - ever - had blisters there before in any other shoe, sandal, sock, toe sock or barefoot combination. Having the individual toes lets the shoe have more grip around uneven surfaces, which is exactly why I got them in the first place. I'm busy trying to grip a 1" wide strap with my feet and walk on it so every bit helps, but it does have it's downsides.