pure speculation
nothing has been tested yet but i suspect once the hype is down and non apple benchmarks are done you will find that the dual 1.4 will be superior at some things that are not super high bandwith related and just as fast at the mudane tasks we use-surfing email mp3 incoding burning cds dvds copying files window scrolling resizing etc.
remember only the dual 2ghz beat the p4 and in quake it was not twice as fast meaning the 3.06p4(and now its 3.2 is faster at most things then a single g5 that can be said against the dyal 1.42
i am awaiting a true test by
http://www.barefeats.com using the same programs on both. i expect alot of people to be suprised, remember a lot of apps are not optimised like those at wwd and may think the g5 is just a faster mhz g4 and not use the extra bandwidth until they are recompiled to 64bit.
like many apps dont take advantage of duals now.
i also want to see the amd opteron 64 bit it has much larger caches then the g5 but only a 800mhz buss. must non apple people think it is the fastest single dual and yes u can get it in quad desktop chip.
apple did not even mention amd even though hypertransport and other amd technology is in thier g5 setup.
anyway i am super interested in seeing all the g5 go up against the g4 esp with the g4 price cuts. i think the g4 will hold its own that is until 64bit apps bring the g5 into its own.
jus speculation hope i am wrong