Chief, although I just ordered two customs from Rudy, Iam hooked. I must have one of those brushes. I think you understand this. When I said hybrid I thought he was using Rooney knot with m& f handles & vice versa & Iam still confused. Iam going to be in London late this month & if I have not heard back from lee, I will attempt to track him on his home ground.
You'll get a prize for that.
Knots don't start out being Rooney, or M&F, or Simpson, or Plisson. They start out as badger hair. Hair from different badgers gets sorted into lots, or at least that's what I assume. Buyer's negotiate to purchase lots. Sometimes those buyer's may be individual brush makes who either keep the lot for exclusive use in making their own brushes, or part some of it off to others. If they sell some of, there might be no real difference between what they keep and what they let go, or they might sort and split it up based on their assessment of comparative quality. My sense is that some lots are bought by individuals/companies who serve as distributors. Where this leads is that I'm not sure how much sense it makes to think in terms of Rooney knots vs. M&F knots. And it's constantly changing anyway, depending on supply. You actually may be making it harder than it really is.
I think the best place to start is by trying some different kinds of knots to figure out characteristics you like, such as 2-band vs. 3-band, knot diameter, loft, density, soft, scrubby, scritchy, floppy, springy, etc. If you're lucky, you'll resolve to a fairly narrow set of criteria that will makes selection fairly simple. If you're not lucky, you'll end up like me and revel in variety.