One tip that is worth repeating:
Get a thick (3/8") maillon rapide and use that to clip the device to your belay loop, instead of using a locking biner
Many locking biners will work around with an Ushba or MiniTrax on the rope and it's always disconcerting to be looking at falling onto a crossloaded biner.
The maillon, because it is long and skinny, doesn't do this - it keeps your harness loop at one end and the device at the other.