ducksterman,

I know your fear! I had the same fear when I started using it. I leave maybe 1/32 tag, but, I am thinking about going shorter. When I hold the fly line in one hand and the furled leader in the other, I can pull really hard on the knot and it does not give at all. I think the harder you pull the more the fly line coating grips the leader. I do not feel it will fail. When you think about it, the rod flexing and the line stretch, there is not that much pressure being put on that connection. Since the tippet has the smallest breaking point, it will break before any other connection. The knot is so easy to tie that anyone who changes leaders often, will find the Castwell knot easier and faster than a nail knot and cutting it off and retying uses less fly line each time. I am sold on the Castwell knot and that is the only one I am using to attach my furled leaders to my fly line on all my rods.