i dont believe that is true. if anything the war's shown us its the reverse. not one of these past legendary shinobis was taken out fairly in 1 vs 1.
4th kazekage hasnt shown much versatility with his gold or ability to harden it into objects or into different shapes. plus he seems rather slow. they saw this guy take down shukaku, saw gaara vs deidara and STILL said "nope sandaimes the best ever". i believe the hype. gaara seems a bit more versatile and has greater quantities of sand but third's magnetite is harder and can form whatever shape he wants via magnet release. and chiyo for backup is too much for team 1
Sand> Gold and gold is denser than iron.
nope. magnetite is harder than gold or iron. density is how much fits in one space. hardness and toughness is how much abuse it can take. gold > shukakus sand as stated by 4th kazekage.