Scraping Cybenetics' reports for 20W efficiency ratings and I'll admit that I have no idea how Wolfgang got his numbers for that spreadsheet. If you just look at the report on Cybenetics' site, they don't match what he puts here. For example, the MWE Gold 550 V2 is 70% at 20W but he says 80%.

https://docs.google.com/spreadsheets/u/0/d/1TnPx1h-nUKgq3MFzwl-OOIsuX_JSIurIq3JkFZVMUas/htmlview?pli=1#gid=110239702