Yes, the directions have changed over the years but my old config still works. It's probably not the best for a new Radeon Mediator setup though.
I had problems with the new pci.library 9.8+. The screen will lose sync while using some Warp3D programs (Alan Thellier's Cow3D for example). I don't know if this would be a problem with 2D apps or the Radeon driver but there was at least one bug introduced after pci.library 9.7. The new pci.library is supposed to allow faster ethernet speed with fast ethernet but I wonder if it is broken or the timings are too tight for some setups.
You could try to find an old Voodoo 3 for testing. This would allow you to play with Warp3D programs also.
I've got a Voodoo, but I can't use resolutions that match my monitor with it. I did go back to pci.library 9.7, but I'm not sure if it was needed, I'm just staying there for safety sake right now.
For the time being, I've also gone back to Roadshow. I have better stability with it other than this one benchmark and it now seems to give similar performance to Genesis.
Who knows, it could be a bug there or I may find that I hit the bug during real-world use eventually.
I also found out that I could use netshutdown followed by addnetinterface to safely recover from the netio hang.
I'm able to get a bit over 1MBps now with the settings I'm using, both send and receive in netio (until it hangs and I have to ctrl-C) and using ftp from an in-house server. Those huge dips seem to be gone from what I can tell.
I set tcp.mssdflt to 536, the standard default size, and it actually seemed to help. 1500 is slower here, 1400 was better than 1500 and 536 seems completely safe and fast enough.
I raised the tcp.recvspace to 65536, but not the send. Raising both seemed to cause issues, but raising just this one seemed to pull up the receive to match the already good send speed. I think this was one of the biggest improvements.
In the interface, I set iprequests to 77 (a magic number from another thread that I'm now afraid to touch) and writerequests to 64. These seemed to also make a noticeable difference.
It still seems odd to get such slow speeds, but with the weak CPU and PCI implementation we have, that's probably about the best I can hope for.