I am impressed with how long the batteries last and have changed my
mind about the need to external power.
Altitude is not that big of an issue for me either.

The two things I would like to see is to

1. make the OK button work without canceling the Tracking.

2. The external power would be nice if the unit would power up into
tracking mode when power was applied. I currently need a checklist to
make sure I have everything turned on as it is. Anything I can connect
to the master switch is helpful.

Brian