I'm not saying I'd use PU glue, but the stuff is very strong. If you make a test block by gluing two chunks of oak together, and then bend/hammer it to destruction, the oak will break before the glue. If someone had an epoxy sensitivity PU would be a good choice. Resorcinol would be a better choice. PU is not waterproof and that means "furniture only" to me...but it isn't actually a bad glue. Unless it was left outside in rain/dew all the time a PU-glued airframe would last many years. Leave it in the wet too long and you'd have firewood.
My only "non crunchy" story is of a local builder who is adding every conceivable bell and whistle to his plane. Dome lights peeking through the headliner, N-way adjustable seats, noise makers rigged to the seven-button joystick so it can make machine gun sounds...all mounted by welding 4130 plates to his fuse. many pounds, and years (he's on yr. 9 IIRC), added to the build...and he brags about how he is "building lite."
