I used to think newer digital gear blows away older gear. Untrue to my ears. There's more to a digital player than the DAC chip. Power supplies, output devices, etc. make a big difference. James Tanner of Bryston said they were very surprised at how little difference the different DAC chips made when developing their digital gear. They made a difference, but not anywhere near the differences made by power supplies and output devices. These things don't become obsolete very easily. My mid 90s Theta Cobalt DAC sounds better than the current $500 DACs such as the DACmagic and V-DAC to my ears. The Cobalt retailed for about $800 or so in it's day, if not not mistaken. Higher end models would probably sound better.
What would make me hesitant about an older CDP is the transport life. If it's obsolete, when it goes it can't be repaired. I'd find out the transport used and confirm that it's still available, especially if the CDP is expensive.