I've been thinking about switching to sup a few times, but the inability to sync changes back to the IMAP server is a deal breaker to me.
If I mark an email as read in sup, I don't want it to show up as unread on my phone. If I delete an email on the phone, I don't want it to stay in sup.
I know there's been a branch of sup that synced IMAP flags from the local repo to the server, solving at least the read status problem. But it seems the version linked here does not include that branch.
FWIW, I never considered that a serious limitation. On my phone, I don’t want to read email. It’s a sub-par experience, especially if you’re used to Sup/Gmail/Notmuch. You can’t just go back to “regular” email clients anymore :).
As for using multiple computers: with sup I used to run it in screen and attach that screen session whenever I needed it. With notmuch, I can just tell it to run notmuch(1) on a remote machine and even use a local UI.
I do some email using my phone when on the go, and although I'd like a better sync experience, it's not a showstopper. OfflineIMAP (buggy as hell, but works) can sync unread and flagged/starred status, which is the most important part. In a normal day where I mostly use notmuch, I just batch-archive the day's messages. I don't like the latency of using a remote notmuch, especially when going through a string of 5MB log files (remote debugging a user's mis-configuration) on conference wireless or while tethering.
If you haven't already considered mbsync as an alternative to OfflineIMAP, I suggest taking a look. I also found OfflineIMAP buggy (many years ago) and mbsync has been syncing my mailboxes reliably since. http://isync.sourceforge.net/
I say this as the author of a program that runs mailbox syncers like mbsync when there are changes to sync (mswatch: http://mswatch.sourceforge.net/).
I agree that this limitation makes it really hard to fit sup into a workflow that includes multiple workstations and phones/tablets. Hopefully they get that sorted.
The genealogically related 'notmuch' can do that: by default it syncs certain notmuch tags (like read/unread) with Maildir flags, and then you can sync Maildir with IMAP using something like offlineimap.
If I mark an email as read in sup, I don't want it to show up as unread on my phone. If I delete an email on the phone, I don't want it to stay in sup.
I know there's been a branch of sup that synced IMAP flags from the local repo to the server, solving at least the read status problem. But it seems the version linked here does not include that branch.