Yeah, it would be interesting.
here's my guesses
1: NetBSD/Linux will probably be able to more consistently make better use of both onboard and nubus ethernet hardware, you might even be able to get more than 10 megabits out of the nubus card
2: These tests are already using IP -- AppleShare 3.8.3 ("for 8.1" but you can run it on 7.6.1) and 3.7.4 ("for 7.6.1 but it'll run on 7.1+") add IP
3: you might be able to get better out of, like, netscape 4 -- I saw big differences between netscape versus IE on, for example, my blue-and-white G4
Someone mentioned possibly using A/UX and some high end disk subsystem stuff to get better performance but I don't know if any of the 10/100 NuBus cards had A/UX drivers. On NewWorld Macs, Mac OS X consistently makes better use of i/o and the available hardware than Classic Mac OS.
This isn't exclusively related to networking but a huge theme for me is just how bad Classic Mac OS is at walking and talking at the same time. If you hold the mouse button down on a menu the whole rest of the system just stops, which is cool. Any Mac with loads of i/o is continuously let down by how bad the i/o is.
On the other hand, it's also part of the charm of the platform and I think it's an important thing to remember how... high end usage of Macs basically until the OS X was almost entirely accidental and Apple's retention of that market into the '90s was based entirely on the Actual Workstation Vendors not being able to get the software ported in a way that makes any sense, not because the actual computers were the best for the usage at hand.