I don't know the Clarity, owned the SL3s 12 years. You should expect to replace the "film" in the stator panel since you are buying used. This may be a significant expense. I'd check with MartinLogan before pulling the trigger. The SL3 is a good speaker but light on bass and needs lots of power to push it. It is fairly "beamy" so the listening sweet spot is very focused. If you are sold on Martin Logan, I strongly recommend buying new.