A few things I would point out as you embark on this effort.
First, love to see this! It is awesome when someone wants to put in the time to experiment and obtain empirical data that can help out the whole team.
I think it has already been mentioned, but you need to distinguish between the strength of the
epoxy and the strength of the
bond.
The strength of the epoxy can be rated by the manufacturer and is usually given by the tensile strength. Most of the epoxies listed so far should have a tensile strength high enough to ensure the epoxy itself is not the weak link, assuming that temps stay within the TG limits of a given epoxy.
The strength of the bond is harder to quantify. I have not seen many manufacturers attempt to quantify bond strength, although System Three deserves credit for publishing their tested strengths with certain materials. For example, you can see that in the TDS of the T-88 product:
https://www.dropbox.com/s/lo9xul8vsx751dq/T-88 Epoxy Adhesive TDS.pdf?dl=0
Although composites are not listed in the materials, the data does show that, in the maple, polyester and concrete tests, the material gave way before the bond. This was also shown earlier in this thread where the body tube gave way before the bond.
Another property that has not been discussed is the brittleness or, more importantly, the flexibility of the epoxies. Generally, the harder the epoxy, the more brittle it is. This has caused me problems in the past. Brittle fillets tend to crack or even shatter and that, I believe, has led to fins popping off the body tube instead of breaking off in some of my MD builds.
For these reasons, I generally use a different epoxy to bond the fin to the body tube than the epoxy I use for fillets.
For bonding the root of the fin, I switched over to T-88 a while ago. There are better and stronger epoxies, but I think, for the cost, T-88 is a strong epoxy and provide excellent bond strength. Once the fin is bonded to the body tube, I put another small bead of T-88 at the root edge of each fin - basically a very small fillet.
For fillets, I have switched over to a flexible epoxy. I tried very expensive epoxies, like Scotch-Weld 2216, but, at $20 an ounce, it isn't very practical. West Systems G-Flex provides a decent tensile strength, excellent bonding strength and is rated for a 32% tensile elongation flexibility, which is super flexible. Once I switched to G-Flex, I have not had a fillet crack, break or fall off. I have also not had a fin pop off.
The way the OP described the testing environment is useful and I look forward to seeing the results, but additional tests at different temps, using different epoxies for the root bonding vs the fillets, and also a test that pulls the fin straight away from the tube would provide additional useful data.
We want to test the limits of the epoxies in this test, so we are not discussing tip-to-tip composites, but, obviously, the point of tip-to-tip composites is to address some of these short comings of epoxies alone.
As with any glue thread, once you go down the rabbit hole, it is a wild ride in wonderland