I seem to remember reading that the 'new' F22 fighter uses 270v DC. Not too sure why - one problem with DC is the switchgear needed - with AC, as the volts go through zero, provided the power factor isn't too bad, any arc extinguishes.
800Hz was used in some WW2 airborne radar. There was appreciable weight saving in transformers - and, for that matter, a saving in transformer quality steel, which was another consideration.