Is the EGO 880 CFM worth the upgrade over the 615 or 765?

It's contested. protoolreviews praised the 880's top-end power, but an r/egopowerplus thread flags that you must use a 4.0Ah or larger battery to access speeds above 50%, which some owners view as a regression. Other r/egopowerplus posters who upgraded from the 765 report being happy with the extra headroom.