Is the dongle connectivity any more/less efficient that BLE? IE, should you seen much difference in battery life while using the dongle vs BLE?
Uhk dongle operates over ble. It supports slightly lower latency than most devices, so it might consume slightly more energy, but i expect the difference to be negligible.
The main trade-off is better reliability and better support since we have control of both sides of the communication with the dongle. (To manage expectations, yes, bluetooth support has been troublesome.)
Regarding battery, right half has significantly bigger battery for exactly these reasons. Turns out that in practice, left is draining significantly faster than right.