BetterZip's big advantage that comes from the way saving works is undo support. That would get lost when directly modifying the archive with every action. I'll think about it, maybe BetterZip could automatically save the archive when you close the window.

Thanks for your reply. I believe that saving upon closing the window is the behavior that Springy uses and really the only thing I miss when using BetterZip. Any consideration greatly appreciated!