I use the Medtronic 722 and have never used the PING. The Minimed is a good pump, but my feeling is that the PING is equally good with more user-friendly options.
The PING is supposed to integrate with Dexcom someday… and the Dexcom CGMS gets much better reviews than the Medtronic system (though the Medtronic system does work for SOME people).
Here is a recent discussion where many people offered their opinion comparing more pumps.