Hi James,
The main reason we suggest doing a full manual ‘upgrade’ (even though your Classic was already running the latest - 20180520 - software) is that incremental upgrades update the ‘PilotAware’ part of the software, but your Classic is almost certainly still running on an older Raspberry Pi ‘Kernel’. (Think of it like updating to a new version of ‘Microsoft Office’ but still running on Windows 95).
Depending on which Kernel your Pi2B is running, some of the newer functionality introduced in 20180520 may still not be available to you. A full manual update will install the latest Kernel available at the time 20180520 was ‘built’ and will fully support all the additional functionality which that version introduced.
I hope this clarifies the position.
If you decide to do a full manual update, remember that you have to fully reformat the microSD card first using SD Formatter (Full Overwrite Format, with Size Adjustment ‘On’ - to delete the existing card partitions and reformat to FAT32). See the manual update instructions here....
https://pilotaware.com/wp-content/uploads/2016/09/160901-Manual-Software-Upgrade-1.pdfAny probs come back on here.
Best Regards
Peter