So here's the weird thing I'm seeing.
I have 3 Gmail accounts (personal, work, and family) and one IMAP account (work). I set up the 3 Gmail accounts in the Gmail app, and the IMAP one in the email app, with the email app set to poll every 5 min.
If I send email to one of the Gmail accounts, I will only get notified if that's the account currently active in the Gmail app. I.e., whichever account was last opened in the Gmail app, that's the one that will notify if it gets an email. Because there's no unified Gmail account, it seems that notification only works with the last Gmail account accessed by the app. Does that sound plausible? If so, it's a drag. I guess I could consolidate my Gmail accounts (I don't like have 3, anyway)...
SRV