I've played one-keyed flutes, and I can tell you that they are a mother-bear to play in tune. Cross-fingering doesn't work nearly as well on a flute as it does on a recorder, oboe or clarinet. You can tell if one of these is being used in a recording by the F, G# and Bb being either out of tune or at a lower volume level. The 4-keyed flute of Mozart's time didn't have the intonation problem, but both 1- and 4- key flutes have a very fuzzy attack. Dead give away in a recording.

Pitch ~1700 and earlier was A=405. That rose to 415 for most of the 1700's and 1800's. The modern pitch is 440, although some orchestras like the Berlin Philharmonic are rumored to use as high as 456 to give the orchestra a "bright" sound, something like plywood cabinets. OK, I'm sorry. I'm sorry. Anyway, all of my recorders are pitched at 440 so they can be played with modern instruments.

Bob