Good Card Still.
I'd go for an AGP ATI for an A1 however.
Firstly you'll need a PCI busboard to use it on an A1200 / A4000 which means putting the A1200 in a tower case.
A new A1200 + Mediator + Blizzard PPC (If you can get one) will cost you more than a New A1 G3 SE and wont be as powerful.