I've never worked with fiberglass, so that was not a consideration for me.
It will be interesting to see how well the hoop holds up. My initial observation is that the diameter of the PVC is too small and that induces a lot of friction, also where the hoop connects to the t-fitting is an area of concern for friction and damage to the sail. My crew suggested to wrap the hoop with some pipe insulation and then use some slick plastic, like what reusable water bottles are made of, and wrap that around the foam. The idea is to provide a larger diameter and a slick surface. I may also consider larger diameter pipe, but the larger the pipe the heavier it is. I suppose I could go with an aluminum ring.
I have been eyeing the Dragoon spinnaker system and if mine does not pan out too well I may drop the coin on that. Only wish I could get it in the states.
I have the Hobie bracket riveted to the front cross bar and then I took an eye bolt, cut off the threads and I mount that with a clevis pin to the Hobie mount. The Hunter boom slips right onto the eye bolt. Perhaps not the most secure attachment, but it works.