Well considering this thread will not be closed and for those still wondering, here is why I think the 550 G2 is superior:
My system has a very low wattage that is going to reduce in the near future. As efficiency curves and stats demonstrate both the 550 G2 and 650 G2 are
most efficient at 50% load in cold and hot temperatures. The 650 G2 is not suitable for me as to use it optimally I would never reach 50% load especially considering the unit's high efficiency (>85%) and even considering degredation over the coming years. The ripple control is superior on the 550 G2. For very low power systems, getting a larger PSU will result in lower efficiency and in this case, slightly lower ripple control. Yes, I am splitting hairs but it's my preference. I just wanted my question answered about resolving this surprise RMA result. I have closed the email account associated with this forum account and I have requested that my account and the thread be closed. I will no longer be able to post here. Thank you again for all your input and I'm sorry if this thread caused you any discomfort.
Edit: Just to add I am very happy to wait months, if necessary, for a replacement model.