what is the forum's thoughts on used speakers? How can you tell that the product is in good working order? Without getting burned. And how old is too old?
To me, speakers are the toughest of all our gear to purchase used, especially as you move up to larger floorstanders. The shipping (assuming you are not able to pick them up in person) can be difficult and the packaging is not as reliable as for our other gear. I trust most packaging for even 100 lb amplifiers more than I would trust most speaker packaging. Larger speakers should be strapped to a pallet and shipped freight. I would be very careful by only purchasing used speakers from reputable sellers, like maybe dealer demos with warranty, or at least dealer trade-ins. Consider buying from long-time audiogon members with positive feedback. If I were a seller with expensive floorstanders, I would sell for less to a buyer who was willing to pick them up in person.
I also like what Lewinskih01 said above, enjoy what you have and listen to other brands. I had a pair of Matrix 803 SIIs that I really liked but I have found Aerial speakers to provide a natural sound that is different from B&W, just as good, and more enjoyable to me. Buy a reputable brand that is going to be around if you need repair, like B&W. The 3A suggestion was good. There are speakers that mate better with lowish powered tube amps, if you are heading toward tubed gear. Coincident my be another speaker brand to audition since they perform very well with tube amplifiers of low to moderate power. The type of amplification needed should be a major consideration in the speakers you purchase. Don't buy speakers that work best with high current SS amps (like my Aerials) if your preferred amplification going forward is tubed.
Good luck and have fun.