West System is a bit picky about how it gets mixed together. It is always better to have just a little extra hardener vs. just a little under the ratio you are working with. A little extra hardener won't hurt it, it will just set up slightly quicker. It also doesn't like to work below 70F degrees. High humidity tends to leave it a bit sticky and slower to cure. It will still cure, you just need to give it a little longer.
The gflex epoxy is really growing in popularity. It has some type of impact modifier in it that improves resistance to shock sheer forces. It takes dye well and is strong, water resistant. It is relatively new. It is put out by the West System people that sell primarily to boat and airplane builders. You know it has been lawyer proofed for liability when it goes into boats or planes.
I routinely use superglue to bond two pieces of material together to drill a hole. I then take a hammer and tap one of the pieces on the edge to pop it off. That is shock sheer force and superglue does a horrible job standing up to that. It has great tensile strength, fair sheer strength, poor shock sheer strength. The gflex stuff was designed to handle that shock sheering load from say a knife being dropped to concrete and landing just right on the edge of handle scale.