Funny how when you do the comparison by looking at those factors, we keep coming back to J-B Weld. J-B Weld has a tensile strength of 3900 PSI; which is 65% the strength of filler metal. (J-B Weld only adheres to the surface, so the bond strength is actually only 1800 PSI). Still stronger than the others. Fro what I can gather, JB is made from epoxy, powered steel, a little chalk filler.
Anyone use this? http://www.cotronics.com/WEB%20SHEET...%20%207032.pdf
I have an email into these guys to check it out.
But it compares favorably to JB.
JB - 500 degree rated, 3900 PSI
RK 454 - 500 degree service temp, 10,000 PSI (but a quick 20 minute working time)
RK 456 - 500 degree, 12,000 PSI (same fast working time)
Durabond 7025 - 1200 degrees, 4800 PSI, No work time listed
Durabond 7032 - 2000 degrees, 5400 PSI, "hardening starts in 60 minutes"
Looks interesting, as long as it bonds to wood or fiberglass, takes a release compound so it does not stick, has low minimum working temps, has no or low shrinkage and has adequate work time (20 minutes is pushing it).