On my Efika with Radeon 9200 I got 70MB/s write, 15MB/s read.
As far as the write performance, I know it is better in a PC. With the AGP riser being plugged into a PCI slot I guess it's not a surprise that it doesn't reach the full performance level.
What do we have to take advantage of these cards at this point anyway? I haven't tried any 3D accelerated programs yet, are there any in particular that run nicely on Efika under MOS?