Over time, Pilot Pro has used Dropbox and iCloud as a way to sync and back up your logbook. We recently went back to iCloud in version 5.0, but we are returning to Dropbox with the release of version 5.5.
Dropbox provides a free 2GB plan. That's more than enough to store your logbook (large logbooks are about 10MB which is only 0.5% of your free storage limit).
The Data Is Yours
The primary downside to iCloud is that you can't look at, or access, your data without Pilot Pro. In some cases, pilots stop flying for a while and set their logbook aside. When they come back to Pilot Pro, their data can be inaccessible on iCloud if we've since moved to another app version or sync solution. Using Dropbox lets you keep your logbook in your own Dropbox account for as long as you want.
Dropbox will let us support Pilot Pro on Windows, Android, and other platforms should we choose to do so. iCloud is possible on those, but becomes harder to use than on iOS or Mac.
The obvious downside to Dropbox is having to sign in (iCloud sign in is automatic). We hope this small inconvenience is worth the advantages named above.