2018 - AN EXCITING YEAR

So, my club has a new K21 arriving for the upcoming season. For the price of the glider, instruments and trailer ($140K +/- I think) we might be able to get a used Duo Discus and have some cash left over. For instance, there is what appears to be a nice, 20 year old Duo an W&W for $115,000. Are Duos that unsuitable for training or are K21s simply more robust and better able to handle the inevitable hard landings by students/low time pilots. Both? I have no dog in the fight as the decision has been made and I, as an owner of my own ship, will fly the K21 only for flight reviews the occasional passenger flight. Maybe. We also have a Grob Twin and L23 and either of those is suitable for those needs. I'm just curious.