Id say Im quite knowledgeable on the prices of gibsons. Hours and hours Ive wpend sifting through them and Ive bought a few. Generally the year of a gibson doesnt affect its prices unless its a 50s or 60s. Infact people often prefer newer guitars in beter condition. Its good because you can get a 70s Les paul with a few dings in it for les than a 2000 model. Yeah its true about the wood affecting the tone but If its older than 10 years then an extra ten doesnt make a significant difference.
My hero slash loves his two 1980 Les Paul standards, its the luck of the draw because ever guitar sounds difference, but some sound awesome!