1D.1, 1D.3 or 1D.4?
Possibly might need it. If you get random corruption on the screen or system lockups it will most likely need the fix. This is of course after you have eliminated power supply issues or other hardware troubles. Jens has mentioned on several occasions that power supplies that have noise in the power line can cause problems with the ACA and using a different or heavier duty psu can fix that issue.
My 1D.1 board was experiencing lock ups and random crashes with my ACA1230/28 and I use a modded ATX power supply. I performed the fix by removing E123C & E125C from the bottom of the A1200 mobo and my problems went away.
Though some boards have already had the fix done or don't need it. If you experience problems with the ACA, then you might need the timing fix.