Only for testing, you will use those builds on your own risk. I recommend to create a backup of your user profile before you start testing those builds. Please consider that it even might be impossible to use an existing User Profile after downgrade to an earlier SeaMonkey version if you have used that Profile with a Nightly.
Also see official SeaMonkey Projekt Blog and dev-apps-seamonkey@lists.mozilla.org
Known Trunk issues:
- Bug 1379370 – (2.53BulkMalfunctions) SeaMonkey 2.53 malfunctions/errors
Known SeaMonkey 64Bit issues:
- Bug 1226839 – 64Bit: Impossible to make Mail/News default application (for “send from Files Explorer”, “Send document (as PDF)”, “mailto:”)
- This query!
SeaMonkey Internet Suite 