Quirkster, I've also tested the Gflex with flame and sanding and was able to break the bond by hand with a moderately aggressive effort. The with the 8010 the PE failed before the bond did.
Regarding the Gflex, West Systems tech dept. now recommends the flame but without sanding. This supersedes the printed instructions. There is an article in issue 26 (I believe) in their magazine (available online) which shows comparative strengths. They also recommend gluing within 30 minutes of flaming since it apparently briefly polarizes the surface, enhancing the bond.
The problem with flaming inside the hull, especially at the cam columns, is getting access all the surfaces without melting the boat, at least for me!
Yes, the DP 8010 is specifically formulated for HDPE. Locktite also makes a similar industrial product called 3300. They also have a couple of similar products. I hope to test all three in the next couple of weeks and will report results.
BTW, I also tried some screen material in the capacity of your fiberglass cloth and couldn't get it to stay in place while I applied the rest of the product within the limited time span. It's worked fine without it. But with the Gflex you would have more time to get it set up. Good luck!