Rather than saying it has Audyssey Platinum in marketing speak, I'd specify it has Audyssey XT32/SubEQ and can utilize Audyssey Pro kit. Never liked the metallic marketing grades.
I have a 4520 and can only say it is a fantastic avr. I bought a new one two years ago for $1k but at one point their msrp was 2.4k fwiw (later reduced).
Good luck with your sale....if it were a bit lower priced even I might be tempted but already have more than enough avrs