I agree with Rudy on the D01 knots except I definitely felt scritch with the D01 two band I had. I love the D01 silvertip (three band). Like Rudy said, it is very dense, like the two band, but the hairs are finer and softer with a bit less backbone. The one that I recently bought has more backbone than you usually associate with three band silvertip knots. It has the backbone of your typical two-band brush from other manufacturers. I don't think I have used a regular 2-band. I had a Shavemac brush with a two band knot once that the owner called a "Unique Knot". The card that came with it said 2 band silvertip. To me, that brush was indistinguishable from my D01 2 band so I believe the original owner's claim that it was not a standard 2-band.I don't have any of these brushes, but this is one of the most educational posts on B&B. I will read it twenty more times if I ever consider buying one of these brushes.
Thank you, sir.
Happy shaves,
Jim