RE:Epoxy Butt Splice
I think you're 100% right about the cracking when it's applied thick enough to be used structurally. This application is more of a bonding agent for fibers than a structural glue like epoxy on a fly head. For instance when I use it on a heavy base of thread to hold materials or eyes it turns the thread into stone while not having any detectable "shell" to crack or chip off.
I'll do all my leaders for the season opener and show you when we hook up.