Grab - the bits that waggle are the pin sockets within the connector, and simply plugging and unplugging an XLR in will cause stresses that cannot be prevented... which is why we have problems with our hire gear that uses PCB mount sockets, but far fewer problems with those that don't.

Perhaps your pal who worked at Tektronix was only looking at the short-term (under warranty), and the problems he was referring to were really caused by manufacturing errors... certainly, all modular desks with ribbons between the modules have reliability problems at one time or another, so eliminating that is good.