Kappas are (were?) nice speakers. In a sense, Infinity was Harman's premium speaker like before Revel came along, slotted above JBL. For the (n+1)th time, I deeply regret selling the 9's that I once owned.
Problem with Kappas are refoaming woofers (small issue), and extremely proprietary midrange and tweeters which of course are long discontinued. If those go bad you'll be scouring ebay and playing a seller's market.
I'd have the seller play them at volume to ensure time has been good to them. And then decide if you're willing to keep them maintained if something goes wrong.