How can I try the latest BusyCal without losing my current version

You can evaluate the latest BusyCal by having both the new version and your current version installed side by side as follows:

1. Open Finder and navigate to the Applications folder
2. Rename the installed copy of BusyCal.app to "BusyCal Old.app" (to preserve your current version)
3. Download the latest BusyCal and run the installer.
4. Launch the latest BusyCal and go through the setup assistant.
5. If BusyCal does not automatically connect to your iCloud, Google or Exchange accounts, you may connect to them manually in BusyCal > Preferences > Accounts.

After you install and setup the latest BusyCal, you can quit the new version and launch your previous version from Finder > Applications > BusyCal Old.app (the app you renamed earlier). This way you can have both versions running side by side and easily switch between them to compare features and functionality.