Re: Breaking off at the knot
I don't know much about the surgeon's knot, but I know how it is having knots in the leader break. I use the same kind of set up that you do with the tapered leader and tippet.
I use a blood knot for mine and have only had it come apart once and that was with a big catfish pulling on it.
Another suggestion would be to make sure that you lubricate the knot before you tighten it. I didn't used to and now that I do, I kind of notice a stronger knot.
Hopefully what little I do know can help you some.