In the end I went with GRS for my epoxy. They were very prompt about delivery.
I mixed up a small batch and epoxied some glass cloth across two peices of ply. I let it set for 24 hours and then tested to destruction.
With a lot of abuse, the cloth delaminated where boards were joined together the. Not easily - I was jumping on the boards where they were set up against a step. The plys actually separated.
In addition I glued two scrap prices together with thickened epoxy and a very quick and dirty fillet. After much jumping up and down, I managed to break them apart - the wood broke, not the glue.
I am quite certain I could do a much better job, both of glassing and gluing, so I have every confidence in this Epoxy stuff. 8-)
* Gluing Oak to Ply.
* Gluing Oak to Oak.
* Glassing a trailing edge.