Good to know. I had planned on useing it to eliminate the stiches.
Rather, the boat is stiched right now. I was going to spot weld next
to the stitches so they could be removed, thus letting the fillets be
one continuous bead. Guess I'll go the regular route!

Don't know what you're building, but try to search among CLC forum archives
on tabbing: http://www.clcboats.com/forum/bbs.pl/. Lot of good advices
there.

I had asked the same question myself when building my rowing shell and I
finally decide to tab with slightly (less than mayo) thickened epoxy fillet.
This is because my seams were very tightly fitted and lower viscosity helped
epoxy penetrate the seam. Naturally I was afraid of "unzipping" but the
tension of 4mm plywood certainly wasn't big enough to unzip the hull. I did
have a small accident when I almost fall into the hull and instinctively hit
the inside of the hull, around the keel, with my hand. All my weight (85 kg)
plus some extra momentum was there, at this narrow spot, while the hull was
firmly supported by the sawhorses and it only resulted in cracking 4-5 tabs,
so I have a reason to believe that the strength of the fillet I used for
tabbing was quite big. You'll also find that some builders even use
cynoacrylate adhesives (superglue) for tabbing.