Not sure that I agree with your premise that there's a "great many" EPS components on eBay, or that this is indicative of any dissatisfaction. A quick eBay search using "Campagnolo EPS" yielded ~603 items. A search using "Shimano Di2" yielded 2700+. I don't think either number means anything. I agree that Di2 is pretty much the standard for electronic shifting, but those I know (a few) who use EPS seem pretty happy with it.