Hey Mr. Foss!

I'm curious where you got your information about the 40%?  I'd be surprised if it were that much.  I use a Babolat machine that uses a constant pull method (which is about 5-10% tighter than a spring tension machine (Neos).  When you're tieing off the head knot, unless you're very diligent to wiggle the knot deep between the two tubes.  The knot near the thoat is easier if you lock the turn table and pull from near the head, the knot will sink down in-between the tubes.

Oh and I always double tie my knots and I've never had one pop loose.

If you want to talk more about it, PM me and we can talk!