It’s actually Android 5.1.1, on a moto G version 3. I assume this is why the bootload itself worked OK, though there still appears to be some caching problems.
I also had difficulty swapping between apps running on the moto G and a Nexus 7 (2012), also running 5.1.1 (and with a patch app that enables the unsupported BLE). I had difficulty releasing the mooshimeter from one device so that it could be seen by the other.
If you were to update the bootloader for later production units, what would be needed to replace it on older devices ? The CC2540 is quite widely used and the CC debug adapters available cheaply, if that’s what’s needed.