Larry,
FWIW, I have Nail Knot that are 3 years old that have withstood 10's K's of casts and K's of ish with zero problems.
They are on shooting heads so they go thru the guides at least twice per cast.
They are covered with Pliobond and are still working just fine. I have never had a knot covered with Pliobond give me any trouble.
But I don't leave my rods out in the hot sun - mainly a cool night fisherman.