I wonder if there is a way to re-set it in flight ? Id imagine not since it could not set a reference pressure on both sides.

If it only records and remembers max speed, it would tend to pick up transients from turns and dives. I guess that is ok, most of us like those screaming dive speeds anyway but it would be handy to evaluate level flight speed too.

Edit..... it helps to read the instructions..... apparently you can set it up to capture data on command using a transmitter switch. Nice.