I haven't seen a benchmark,but i can only tell you from the ones i run:
a4000,Warpengine 040-060 adapter running 96mhz, Acard 7720U,ide adapter,Sandisk extreme 64gb=9.4MB/s
a4000,Cyberstorm MKIII 060/50mhz UWscsi Acard 7720UW,ide cf adapter,Sandisk extreme 64gb=27MB/s , with real 10K HD,no adapters etc=38MB/s,with acard 7730A scsi sata and samsung ssd=27MB
Cyberstorm ppc about identical speed and setup as MKIII.
Quikpak 060 for A4000T,060-50mhz,edo ram,Acard 7720U,ide adapter,sandisk extreme 64gb=8.3MB/s
Would be nice to have a list of stuff like this. There is a good Bustest thread over on EAB somewhere.