Buying used vs new speakers from a technology perspective

I remember going to someone's house who demonstrated an Electrovoice 12 TRX speaker installed in his home built bass reflex box.......great sound.

I would really like a pair of AMT 1’s from 1974, sealed box woofer. ESS used cheap woofers in well-designed heavy boxes. The woofers were of the rolled pleated edge surround system, unlike todays cheesy foam surrounds. Rolled edge speaker surrounds do not rot or turn to dust.  I currently have a pair of Electro Voice EV7 in the garage.  I would bring them in, except the vinyl clad exterior is peeling in a crappy way leaving a speaker covered in aluminum foil that is glued to the plywood.  1960s technology that delaminates. 

Someone looking to buy the new KEF Reference META or Blade META is asking themselves the OP's question.

Well, I’m still enjoying my Apogee di-pole ribbon planar Divas from 1994. It takes a significant dollar sum in today’s field to equal them

Of course, there are new speaker models every year that have new materials, new crossovers, and new cabinetry. Rel has its newest S/ series or B&W has a new diamond series. We often equate "new" with "improved." In the audiophile world, however, "new" is probably just "different." You might like the difference; you might not. Manufacturers will describe how the latest model is an improvement over the last one--the sub has a stronger amp, a stronger cabinet, a new material for the speaker cone that doesn't lose its shape. And as much as I am interested in the latest and greatest, I try to remember that it's the sound that matters, not the version number.