There are 2 woodwind instruments that come to mind when I think of a high pitched solo. Those are the flute and the clarinet, both of which can have either a mellow or a piercing quality depending on the pitch. But the pitch is not my main concern here. My main concern here is the very fast notes. I know there is a limit to how fast you can tongue on any woodwind and thus a limit to how fast you can play the notes.
The fact that only about 50% of the breath on average actually goes into the flute for any note makes it even more difficult than it would be with just the fast notes alone. In contrast, nearly all of the player's breath goes into the clarinet meaning that on average more notes can be produced per breath.
The reason that I am considering having a woodwind solo here as opposed to a violin solo is, well really 2 reasons. The F6 is difficult on the violin for an amateur. But even if I wasn't taking that into consideration, the other reason is the timbre of each instrument.
Out of all the solo instruments I would consider(those being flute, clarinet, oboe, and violin), the flute and clarinet have a more mellow timbre compared to the piercing timbre of a high violin and the nasal timbre of the oboe. The flute is more mellow than the clarinet at high pitches. A mellow timbre fits perfectly with the piano dynamic of the solo.
This solo comes right after a 1 chord apotheosis in full orchestra in my orchestration of the Pathetique Sonata. Here I will show the measure before the solo and during it. The tempo is at quarter note = 33 BPM
The top melodic line in the treble clef of the second measure after the first eighth note in the image is the solo. The 3 lines below it are what I plan to be orchestral strings and possibly some horns as well. The first eighth note of the second measure and the entire first measure in the image are orchestral.
Is this solo too difficult for a flutist or should I have the clarinet play it?