Both the OB-6 keys I currently own and the OB-6 module I had are entirely rock solid. Also, just because the particular synths you tried creek, doesn't mean anything as both the P6/OB-6 chassis are made of steel, which means it's not as flexible, but it's a high quality material and strong.
Either you are being extremely hyperbolic, you're the Incredible Hulk, or you tried one on a show floor where some folks actively go out of their way to break things. The store I go to doesn't carry Sequential products, although nearly everything there is always broken, especially anything to do with knobs.