In the main text we keep the Chopinesque A notation, in which 
, although slightly closer to the bottom stave, probably refers to the parts of both hands. The clarification in GE (→FE,EE,IE), certainly compliant with the performance resulting from the A text, can be considered rational and regarded as a practical variant, drawing our attention to the quasi-canon-like dialogue between the hands.
As far as the position of the mark is concerned, either in the upbeat or at the beginning of bar 1, both can be found in Chopin's pieces (cf., e.g. the Etude in A
, Op. 25 No. 1 and in A minor, Op. 25 No. 4), sometimes even within the same piece, e.g. in the Mazurka in C minor, Op. 30 No. 1. Although it is difficult to guess what Chopin's motivation was when choosing one of the versions, it does not seem essentially important, practically speaking.
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category imprint: Differences between sources
issues: GE revisions
notation: Verbal indications