Monica, I hope you'll excuse my late arrival to the party. I offer some of my thoughts in our "virtual masterclass" here on PS (some of which may be controversial). As far as the etude nature of the piece I offer that it bears remarkable kinship in spirit to Czerny Op.740 (The Art of Finger Dexterity) No.17, possibly Op.299 (School of Velocity) No.26, but mostly (for me) the Moszkowski Op.72 (15 Etudes of Virtuosity) No. 6 in F major. IMO, the piece is
best approached as an
artistic etude. In fact, if I were sitting on an Oral Board of Examination for an advanced candidate in Piano Performance and Literature, and admittedly wanted to stew the candidate, I would ask if Schubert composed any Etudes. And when the candidate answered "No," I would follow with "What about the second Impromptu of Op.90?" The point being, not to be so limited that we forget to see the
music at the cost of the title (as I said before, "A rose by anyother name is but a rose"). This fist step may be the most important and controversial, Do I approach the work by the nature of its title or its betrayed purpose? I think it makes a very big difference. I think it should be approached as if it were an Etude of your favorite etude composer (Cherny, Cramer, Clementi, Chopin, Henselt, Liszt, Moszkowski, Moscheles, Haberbier, etc.)
First, so that we're on the same page of music, the first note is in measure zero (0). As such the
Ben Marcato ("B" music) begins at m.83, the return of the "A" material at m.169, and the "Coda" at m.251 (but this is false, as it is the "B" music; the real Coda, is not a Coda at all but a
Codetta that is from m.276 to the end). That completes the overview.
I think the entire "A" section should be played without pedal, as the very nature of the thematic material is scalar and creeping chromaticism. This first section should have "sweeping" motion of dynamics that rise and fall and climb even as a roller-coaster does. With so many fast notes in the right hand, the notes themselves become less important and the work of the pianist is to shape the groups and phrases. The absolutely worse thing anyone can do with this work is to "turn the right hand on" and let it play like a machine gun. This balerina needs "sparkling delicacy" that is "supported" by the male dancer of the LH. For the section at m.26-, please voice the RH half notes fully, recalling with them the second-beat half notes of the LH material (if you don't think of it as such, you won't play it as such). Sometimes here the right hand is "required" to do some thumb/hand passing, or is it so? Have you thought that on occasion (m26, 28, 30, 32, etc.) you may play the down-beat first note of the RH
with the LH? This way you don't have to do the crossing with the RH. Having come this far and noting the importance that Schubert gives to the 2nd beat, is it possible that it changes the way that we play the LH at the beginning? I think it does. For me, I see now (in analytical retrospect) that the sounding of the second beat is as significantly characteristic to the work as any other feature. Think about it. To wrap up the first departure and its return, I would make a big deal about voicing the Cb in the LH in measure 49 so as to carry it through to an audible resolution on the Bb in m.51.
Reagarding the Ben Marcato in m. 83, the most important thing I can say, is that Schubert failed supremely in the manner that he wrote his enharmonic modulation, and if you play it
his way, you are starting off on the wrong foot. This is what I mean, the Gg major chord that serves as dominant to B minor is a
huge sublimation! I would "change" the Gb major chord of m.82, to an F# major chord! Don't laugh, it makes all the difference in the world. Think about it. In this section I would use some judicious pedaling, but never allowing scalar melody to co-mingle the notes (meaning
if you use pedal in m.85, you will need to change it on each beat) . The phrases here are four measures long and should be articulated with a break in between (just because he doesn't "compose" the [breaths with] rests doesn't mean there aren't any. I know you know what I mean.) At m.105 the RH should begin with fingers 2/5, no pedaling, always maintaining the prominent E# resolving to F# (which should be shortened so as to take a breath as the last note of the four bar group). (Last sentance is of course the same for m.149, etc.)
At the improperly labeled "Coda" (now clearly seen as just "B" material, making the auditor think it is a rondo or repeated binary form), again enter with an F# chord not a Gb chord

. Here I will comment directly to your interpretation and say that just because the second four-bar group (m.255-258) is in eb minor, it in no way means you should draw back on the force of the statement. You do the prior phrase with nice attitude, but then retreat when it shifts to the closing key. I would not do that; I would maintain a strong character throughout. The only dynamic from here to the end is
FF with several
fz thrown in for good measure! My score (the Breitkopf & Hartel reprint by Dover) shows the accelerando beginning m267. Harmonically, he writes a hemiola for bars 280-281 (i.e. meter change to 2/4). Don't be afraid to play it that way:
1,2,
3,1,
2,3,
1. You have a slight hesitation on the penultimate chord that spoils it for me (can you close the gap with editing?)
There you have it. Admittedly more about the work than your performance, but I think it is important. The big take away that I would tell you is, "Play it like a great etude and damn the torpedos!"

Don't use any pedal if possible and think about the interpretive and "applied techinique" issues I listed above. Personally, I think you have the piece ready now to simmer, and when you return to it, you may have a
masterful performance.