My biggest issue with Modest, and I accept that my large mailboxes are a likely culprit, is that Modest will work for a few days then stop updating my inbox. If I delete the .modest/cache/mail/imap/my_account folder and restart Modest then it works for a few more days. I am accessing my mail via IMAP and have ~ 7000 messages in my Inbox.

My second and perhaps more annoying issue is that Modest lists all messages including messages deleted or moved by Thunderbird.

The third and perhaps most annoying issue is that I often find duplicate copies of messages listed in Thunderbird after using Modest.