I thought that the reason there has ever been more than one clarinet was to make the music easier to play in different keys.
Would you be transposing the piano part to fit or transposing the clarinet in bb part to make an A clarinet fit with the piano?? - if that makes sense what do you think?
If you want to play a study on A clarinet I can't see that it would matter as long as you played from the music as written as the written music must have been the criteria for selection with regard to technical difficulty etc.
No doubt there is an answer on this website somewhere!