This might help with "bad pairing" where a pebble wont connect anymore after toggling bluetooth on the watch
A workaround was to scan bluetooth before connecting after toggling bluetooth on the watch
HOWTO:
1) Pair you normal Pebble (not necessary if already done), make sure it was connected once
2) Unpair your LE pebble if already paired
3) Switch on "Always prefer BLE" in Pebble Settings
4) Tap on the + in Control Center to add a new device
5) Pair your Pebble-LE XXXX or Pebble Time LE XXXX inside Gadgetbridge's Device Discovery actibity
Now Gadgetbridge will connect to your LE Pebble when tapping on Pebble XXXX if "Always Prefer BLE" option is enabled.
You can easily switch back to classic LE by turning that option off again
Wait a 0.5s after each complete Pebble packet and do not longer wait at all after a completed GATT package chunk (was 0.1s)
Big outgoing messages will be now much faster such as firmware installations but smaller take more time than before.
(This is not the proper fix but I could update the firmware this way, failed 10 times before after a few percent)
It seems that setting the MTU on older pebbles does not work, so just use what we can use.
Maybe old pebbles need setMTU() which only works on Android 5+, we could use that conditionally...
Andreas Shimokawa