There has been continual improvement of speaker technology over time. If I think if the stuff of ever 2000, or 1990… in dynamic speakers… there is no comparison. Typically, I would say buying 10 years old at half the price is a screaming deal. But after that, beware.
I have owned a half dozen sets of speakers in the last 40 years. But I have auditioned dozens more. While some planar speakers of old are spectacular, they excel at a few attributes, not all. Planar, have strengths an weaknesses. After ten years regularly attending the symphony I switched back to dynamic and realized why they are the mainstay of the industry. They can do everything well. And the are moves forward year after year improving.
So after ten years, the improvements obsolete the older models.