If you want to see the results, this thumbnail links to the bigger one.  My head hurts a little after looking at this....
[url=http://videosean.gotgeeks.com/i/Ziggo5/NetTest_Big.jpg][img:f82e505ffe]http://videosean.gotgeeks.com/i/Ziggo5/NetTest_BigT.jpg[/img:f82e505ffe][/url]
http://videosean.gotgeeks.com/i/Ziggo5/ - all of the individual images are saved in there too.  From what I can tell Z2 is a better server than Z5 no matter which cable I use and the bandwidth numbers from this test are higher than anything I ever see copying files from Z2 to Z5.  I get what you're saying about 40-50% from Disk I/O but that can't be the only thing limiting the speed... if everything were equal then I'd see 40% max ethernet and firewire, not 40% FW and 70%E.  I can be happy that firewire is still faster but it should be more faster... the spec is higher and the path is shorter!  I know... I'm crazy...
[img:f82e505ffe]http://videosean.gotgeeks.com/i/Ziggonet_F/001.jpg[/img:f82e505ffe]
:)