Great job guys! Things like this together with CalDAV and CardDAV are reasons why I pay you guys for service.
I just tried the following experiments with my Gmail and FastMail account. There's a reason why FastMail just feels faster!
Try this:
1) While having the Gmail iOS app open, mark an email as read on the web
2) See how long it takes for Gmail to reflect the change
3) Now try with FastMail iOS app, see that it's faster
Try this too:
1) While having the Gmail iOS app open, delete an email on the web
2) See that Gmail app never updates until you manually refresh
3) Now try with FastMail iOS app, see that it happens instantly
How about the other direction?
1) Read an email on your phone
2) See that Gmail on the web never updates until manual refresh
3) Now try with FastMail... Instant update!