Yeah, I too have been using for about 30+ years. It is poly which is why it adheres so well, It does fade in color in the sun. I have used for everything from teak adhesive
, portlites, thru hull
fittings, chainplate sealant
, and under windlasses and bow sprits. I have never seen it crack, it does get pretty firm, but I sure cant see it getting hard enough to actually crack. Have you actually seen it (and know it's 5200) crack? I've never had a leak or failure on something I've done with 5200. Not hard to get metal fitting off where its been used, but wood and other things... it's a bear for sure....