That’s a good question. Let me explain.
The major features I planned for version 5.0 were a Yosemite look and feel, a geocache images tab and a location picker (to choose a location for corrected coordinates, API searches and home locations. See screenshot).
To implement these features I had to make major refactorings in the existing code. For example, for the location picker I needed the Apple Maps API, which is only available for Mavericks and higher (so that will be the minimum OS for version 5.0). That made it possible to replace a lot of legacy code by more modern APIs Apple is providing. Or another example; to add the photos, I need to do a database version migration. That provided the opportunity to make the data model more efficient (loading at startup with big databases!), and prepare for new properties (user waypoints). The extra work involved was to create a migration process from the old to the new version, keeping your old data work in the new version.
These refactorings make the groundwork of the application more stable, faster and better maintainable. But they cost a lot (yes, I mean a lot!) of time. And in the meantime there is still some maintenance work on version 4.x…
To make this version ship in a not too distant future, I will cut some of the planned features (probably photos too) for the first 5.x version. But a lot of groundwork has been done, so those extra features can be added soon after the first release.
All these changes in the foundation of the application, might introduce new issues, and that’s not what you and I want. Therefore I want to do thorough tests upfront. I also want to do a public beta within a few weeks (just like Apple does
If you want to participate, please send a mail (using the contact tab on this site) and mention ‘Public beta’ in the subject field. But keep in mind that the first beta will not work with your current database, and the final version will probably not be able to use the data from the beta version too. The main goal of the beta is to gather feedback and find bugs, not (only) to make you enjoy ‘the latest greatest’.