TL;DR
Both 80bpm and 95bpm (half-note beat) are within the range of tempi Chopin designated for allegro, though 95 is at the extreme.
The autograph copies of Op. 66 only indicate Allegro Agitato, without metronome markings. The first French edition is marked half-note = 84, and subsequent editions follow suit. However, these publications were all posthumous, so Chopin could not have been consulted on the final production.
Where there are autographs from which some inference might be drawn:
- Etude Op. 10, No. 8 is marked 2/2, Allegro, half-note = 96.
- Etude Op. 10, No. 9 is marked 6/8, Allegro Molto Agitato, dotted-quarter = 92.
- Etude Op. 10, No. 12 is marked 2/2, Allegro con fuoco, half-note = 76.
It's also clear that Chopin was directly involved in the publication of the Op. 10 etudes, so it's noteworthy that No. 1 was published in 4/4, Allegro, with quarter-note = 176; and No. 2 was published in 4/4, Allegro, with quarter-note = 144.
No. 2 is sixteenth-note driven, so at quarter-note = 144, we have sixteenth-note = 576. No. 8 is driven by sixteenth notes. Translating half-note = 96 gives sixteenth-note = 768. No. 9 is also driven by sixteenths, so from dotted-quarter = 92, we have sixteenth = 552. And No. 12, sixteenth-note driven, given half-note = 76, we have sixteenth = 608.
In terms of sixteenth notes, we're left with:
- Allegro Molto Agitato = 552 (No. 9)
- Allegro = 576 (No. 2)
- Allegro con fuoco = 608 (No. 12)
- Allegro = 704 (No. 1)
- Allegro = 768 (No. 8)
In other words, among the Op. 10 etudes, Allegro tempi range from half-note = 69 to half-note = 96 (quarter notes = 138 to 192).
Given the wide range of tempi, and assuming Chopin's metronome was consistent, the primary conclusion is that Chopin used indications like Allegro Molto Agitato to describe musical feeling more so than literal speed. That is, the latter depended on the former. One could speculate that this is why, after using very specific metronome markings in his early works, he abandoned the metronome later.
The information in this post comes from Thomas Higgins, "Tempo and Character in Chopin", The Musical Quarterly 59/1 (Jan. 1973), 106–120. Of particular note is the appendix, which given tempi according to Chopin's autographs and the published versions — there are fascinating differences. The various autographs and first editions can be seen at Online Chopin Variorum Edition.
