I have not listened to the Pickering yet. It just sort of hit me in a way when I received it that you really are taking a serious risk with some of this stuff.
Remember Raul who own 100+ vintage cartridges and still fascinated about them. There is a very little risk, especially if you're buyin them from a fellow collectors, not from the professional sellers.
I'll tell you that i've had more problems with brand new cartridges and electronics than with a vintage ones.