Lee--

I tend to think of fillets the other way around. They're a mixture of epoxy with light, low density, low strength fillers. I see them as a way of radiusing the inside corners so the glass will lay smoothly from panel to panel. So if I didn't want to use tape on my inside seams, I'd fillet and apply 4 oz. cloth over everything.

Interestingly, I looked in "The Gougeon Brothers on Boat Building" and found some information on types of fillet failure related to wood thickness, fillet density and failure mode (wood or fillet failure). But my quick search didn't turn up anything on glass over fillets.

Mike