Zorros are indeed cool but I couldn't agree more with Alexh.
Deneb is blazing fast with DMA usage and USB2.0 work as intended.
I had an A4000 with both Deneb and Xsurf and I can say, I'd choose USB NIC any day

After all you can leave your precious Zorro slots for other important hardware... (hint: RTG Card, ZoRAM, etc)