I received my card today and installed it in my Amiga 4000 on the X-Surf-100 card. I have it running along with my Deneb (running in PIO mode due to ZoRAM). I did a quick test of the two controllers using my external HD formatted as FAT95.
Deneb - 5,461,333 bytes/sec
Rapid Road - 6,553,600 bytes/sec
I think the Rapid Road is a good card to get if you want USB. Happy with the performance of it too! The only advantage the Deneb has s the 4MB flashROM which I rely on these days.