The change of the nature of the sign performed in GE1 requires a careful examination. The sign written in A, although very big as for an accent (even long), clearly applies only to one chord, which determines its meaning (the atypical size of the sign is proportional to the amount of space Chopin had to fill with two crotchets of the 2nd half of the bar). However, the engraver of GE1 could have assumed that a sign of such a size must be a diminuendo and upon seeing the beginning of the sign having been written clearly before the first chord, he started 
a crotchet before that chord. In this scenario, the only authentic sign is the long accent in A.
On the other hand, Chopin proofread GE1, hence this kind of an unobvious change could have been introduced by him. A few observations seem to confirm that possibility:
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Dynamic markings in the recapitulation are very sparse in A – from the entrance of the soloist in bar 268 to
in bar 299 there are no dynamic indications except 
or hairpins. In the next bars there are also no indications of this kind until dolce in bar 311. What is more, in the second section even the hairpin appears only twice ( in bars 303 and 305), which, together with the abundance of accents, suggests an entirely loud, turbulent and raging music. Of course, the absence of indications does not have to correspond to the absence of changes, yet the addition of a hairpin in the discussed bar 300 seems to be justified in this context, which at the same time increases the chances of authenticity of this sign. -
The change of the accent to is accompanied by the change of slurring, which may be regarded as coincident with diminuendo. A longer slur suggests a smoother and calmer performance of the final section of the semiquaver passage.
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The absence of the
sign can be related to a gradual extinction of the sound (e.g. in the Waltz in C
minor, Op. 64 No. 2, bars 15-16), which also coincides with the indication.
In the main text we give the accent of A as the undoubtedly authentic sign. The hairpin in GE1 may be considered to be a potentially authentic, equal variant. Variants of this sign in the remaining editions are a result of either inaccuracies as in the case of FE (→EE) or revisions (GE2).
Compare the passage in the sources »
category imprint: Graphic ambiguousness; Differences between sources; Corrections & alterations
issues: Long accents, Inaccuracies in FE, Authentic corrections of GE
notation: Articulation, Accents, Hairpins