Its rare enough for me to spot a pair of 20 hole Doc's but over the knee ones? Very interesting although I doubt I'll see any on the streets around where I live.
As for breaking Doc's in, thats one of the problems I'm having and have been with a particular pair (I have two) that I've owned for around 2 years now.
They are the kind with the steel insert toecap, basically gives the toe a raised appearance over the "standard" style. Anyway, I've had these for some time and have tried wearing them but no matter what I do, including 3 pairs of hiking socks, they always end up skinning my feet which is rather painful! As for the other pair, I never had much trouble, after a couple of weeks, I could walk a few miles in them. So perhaps there's what people in an industry would call "production variation" going on?
I've seen Docs with side zips as well. Hmm not sure what to make about those...