To just add a note to your excellent piece Scots........

The PVA glues do indeed have a plasticizing agent which also helps absorb shocks...BUT, anything that absorbs shock also absorbs sound! There are a couple of PVA's available that dry hard and are far superior to the carpenter's glues. One is available from Luthier's Mercantile.

I don't know which marine epoxy you are thinking of, but I personally believe that the best by far is WEST System Epoxy (Gougeon Bros. in Michigan, best source is West Marine--not related)and it is also available to the hobbiest types in usable quantities.

And as you said, nothing beats the proper fitting of any joint.

Spaw