> AFAIK, the theoretical max transfer on NuBus is 40MB/sec.

I'll take your word for it.

> on my Quadra class machines is 6.3MB/sec with interleaved memory on a 
> Quadra 650, so I imagine that would be a limiting factor on any RAM 
> to NuBus communication.

Yah, I'd expect so.

> I'm not sure what other limitations there are, but in my ethernet 
> testing with NuBus and onboard ethernet in my 68k Macs running 
> NetBSD, the best I've seen them do is 380k/sec.

Is that testing to/from disk, or to/from memory (with ttcp or ftp
to/from /dev/null & /dev/zero)?  That looks suspiciously like a
disk transfer rate.  Was this with the on-board SONIC on the Q650?
If it's with a nubus card, how much memory was on the card?

> And if I remember correctly, the 10/100 Nubus cards offered at most a 
> 2x, not a 10x increase in throughput.

That probably depends on the card and the machine.  Sometimes it's not
the throughput that inspires the technology.  For example, if you're
upgrading a network to 100Mbit, you don't want to have to support a
couple of 10Mbit machines...  :-)

FWIW, the Asante on-line store has their 10/100 nubus cards
for US$179.00.

-allen