I am not sure I ever noticed any difference , and I have the same setup (recently taken apart ) 
Does it say  anywhere it will be faster ?
Is normal zorro 2 already fast enough ?  i.e. is the zorro 2 bus  ( through the a1200 accelerator connector) slow enough to limit the data xfer to the card anyway 
 
 How does your benchmarks compare to that card in other amigas with similar cpus ?
There are all massive  guesses , and I could be talking shite