R Lewis,
1. The voltage is supposed to be standard.
2. The outlets are supposed to be standard also
3. I have never heard of any airline favoring either an inverter or standard DC adaptor. RCTA is the body that sets standards for electronics used aboard aircraft. They are the ones certify the inverters and adapters.
4. I haven't any flight staff show interest other than to make sure that electronics are turned off for takeoff and landing.