Yes, excellent point! When I bought my QCTP I wanted a wedge, but could only afford a cheaper piston model. I knew the wedge was superior to the piston when I ordered the piston but sadly money was tight enough that I was lucky to get the cheaper piston, much less a wedge. I think things might have changed in the last few years with little cost difference from one to the other wedge VS piston. I would totally agree on getting a wedge type post if funds allow.
With all that said I have not been disappointed with my piston type tool post in any way.