I thought someone else would shed some light on this one.
Not seeing the pickup, I would presume the pickup to be similar to the other gibson vintage pickups but only with an A3 magnet.
A3 is a bit weaker than A2, so I would think you would get a milder sounding pickup.
Probably great Highs and Weaker Lows than A2, and A5.
It might just be my A3 magnets, but I always thought the A2s sounded better in a humbucker than the A3s, and hard to beat in a vintage wind.
If anyone else has experience with A3s in a 8k humbucker like the gibson custom bucker, please jump in.