I wouldn't bother. Just save the extra money and stick with a Voodoo3.
When I still had my A1200/mediator system, I swapped out my Voodoo3 2000 for a Voodoo5 5500 and everything was just the same as before (maybe even slower, I don't remember exactly as it was a long time ago). Quake was just the same speed, so was Shogo, Freespace...
Only good thing is the extra RAM, but nothing really takes advantage of it so you have to keep opening shell windows and typing "availP96" just to justify the purchase to yourself.
