A3 is, to my ears, the weakest in output of the magnets I ever tried. It makes any pickup sound very vintage, and adds a sweet treble on top. A3 is probably the best magnet for clean humbucker playing specifically, if you're after great balanced vintage tones with a sparkling treble on top.
So if you want to tame some boomyness, don't mind some treble on top, yeah, for sure give it a try. The one thing you will lose, however, is a portion of the A5 output, A3 is definitely much weaker magnet. You will also get a bit less squash/compression and the pickup will tend to exhibit the difference between louder and quieter picking more.
HTH