My current boots are Raichle (old Raichle, not Mammut-owned Raichle). They are about 5 years old, and have had a fair bit of use (although I don't do quite as much walking as some people on these forums). The soles are Vibram, as are the soles on pretty much all decent rugged walking boots these days.
However, these Vibram soles are not one piece, but are made from at least two (possibly more) pieces stuck together. It would appear that the only reason for doing this is to have a pretty two-tone colour scheme in the soles. It sure ain't pretty to me, but I can't think of any other reason they would do it, so I'm assuming it's aesthetically pleasing to some people.
In any case, constructing a sole out of two (or more) pieces, rather than the traditional one piece seems like a step backwards when it comes to strength. What were Vibram thinking? What were the boot manufacturers thinking when they decided this was the way to go?
Anyhow, on my last walk, one of the knobs of the grip on the sole of my left boot came right off. It has clearly separated from the different coloured layer below it and then had only a thin line connecting it to the rest of its own black piece, which of course tore off.

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When cleaning them after the walk, I noticed that a second knob of the grip on the same boot is also about to tear off. The tear looks to be well in line with a join between the black layer of the sole and the grey layer beneath it.

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Has anyone else come across similar problems with Vibram two-tone soles?
This sure seems like a crazy way to make soles, and I'll definitely be looking for single-colour one-piece soles again for my next boots (like I've had on all my boots before this). In the past, the soles on other boots have lasted the longest, merely wearing a little flatter, while the stitching or other components eventually started to break down (after about 10 years). This is what I should expect from soles... wearing... slowly. Not falling apart!
I think I'll be able to get a couple more decent walks out of these boots before the soles disintegrate completely, but it's definitely time to start saving up for another pair. I may finally be able to get the Zamberlans I've wanted for the last 10 years or so.