I now have 3 years project management experience, 1 of which is related to an ERP implementation. As I'm employeed by the bastion of six sigma, all of my pm experience has been utilizing DMAIC, DMADV, and DFSS. You might add a pinch of TtM in there as well as we are partnered with Xerox. These methods are different from the PMI proscribed. If I were to ever look for an outside job, which would be more marketable from a project management perspective, a greenbelt/blackbelt six sigma certification, or a PMI certification?