You will only have the 0-300 or 400+/- yd. capabilities. As the holes on the A1 are set at different heights and the holes in the A2 are at the same center.
The reason I put an A2 apperture on my A1 upper is that I really do not like the small appertures on the A1 sight. The larger hole on the A2 can be used accurately w/ practice to reasonable distances (as long as you understand your rifles long range is limited with this settup) The small hole is kind of obselete unless used during periods of better light, and then the larger is used for lower light. (The shot placement with either will be identical)
If your desire is to be able to shoot at longer distances you will have to use a visual aid (scope, etc.)with this settup or just get used to the small A1 apperture you already have. Or, get an A2 upper and have all the adjusment you ever will need.
Realistically, I don't plan on shooting this particular rifle much past 300 maybe 400 yds, so this settup works fine.