Just finished trying QuickMail, but removed it after a few minutes. It persistently fails to display messages in some, but not all, of my Gmail subfolders. More importantly, unlike Thunderbird, it doesn't fetch my messages automatically. There are 1, 2, and 5 minute options, as well as an "Off" and "let server fetch" option, but none of them makes it feel as instantaneous as Thunderbird. Also, when a folder has focus, tabbing through the folders doesn't automatically display its messages unless I've pressed Enter on that folder first. I wanted to ditch Thunderbird, but I guess it's staying, at least for now.