I have also been practicing my singing, and surprisingly it seems that Theodore likes it, smile.
With regards to upgrading, it's a fair question. You can always check the changelogs from the App Store, and we generally keep older versions on TestFlight that you can access using the "Previous Builds" option in case you need to revert for any reason. In any case, below are the changes from the two versions that have followed since 3.4, so you can decide if you want to upgrade.
4.1 Nov 14, 2018
• Improved behavior in numerical fields, such as currency fields in financial apps. Please let us know what you think!
• Added "Theodore" to the dictionary. My wife and I just had a new baby, and guess what we named him, smile :)
4.0 Nov 7, 2018
• Brand new Apple Watch companion app. You can now send messages straight from your watch!
• Performance improvements to make FlickType even more snappy.
• Updated instructions.
• Reduced memory usage.
• Dictionary improvements.
• Fixed some typing issues when using the half-screen mode.
• Removed "Minimal" size setting, and renamed "Half screen" to "Standard".
• Workaround for iOS bug where switching keyboards is impossible on text fields that expect numbers. FlickType will now dismiss the keyboard instead of attempting to switch to the next keyboard, since the latter would cause a freeze.
• Added announcement when changing keyboard layouts (numbers, uppercase, lowercase etc).
• Removed "Dismiss" key setting - the dismiss key will now automatically appear when in "Full screen" mode only.
• Replaced "Done" button in "Settings" tab with a "Dismiss" button that only appears when editing the emoji shortcuts.
• Renamed "Demo" tab to "Type".
• Other bug fixes.