ECC matters
ECC is required on mission critical hardware.I have spent 36 years fielding embedded devices in core network (D1/E1, SONET, ROADM/MPLS, Cellular basestation) and I will tell you that large ECC covered memory arrays always show small numbers of correctable error events over the course of a year. I have seen, over the course of my career, exactly one controller card replaced early in the field, because it started throwing excessive recoverable ECC events over time, until it hit a threshold of 10x the average of a typical board. On the order of ten recoverable ECC events per  month instead of one event per month. I have never observed a logged non-correctable ECC event in the field. In the lab, yes, but never in fielded equipment.If you are fine with your PC experiencing one or two bits flipped in memory every month, then you really don't need ECC. That is the question you need to answer.For mission critical systems? ECC is a requirement.