Note: The splitting of RAWs and jpgs does not seem to be able to be implemented using a tether and DPP. (ie: RAW to card and jpg to computer)
That said...
Here is pretty good news. I updated my Mac to Leopard and via Boot Camp I installed Windows XP Family, the Canon DPP software, and a program called Mac Drive 7 from:
http://www.mediafour.com/products/macdrive/bootcamp/.
Mac Drive allows the windows partitioned laptop to see the mac side partition of the drive,
as well as Mac formated external drives. I allocated 8 gigs for the Windows partition. I am
not planning on keeping any files in it due to Mac Drive and the OS takes up a little over 5
gigs.
Getting everything installed and sorted does take some time but Boot Camp walks you
through it.
So to capture...while in Windows I set a folder in the Mac side of the drive to receive the
CR2 files. I opened DPP and the EOS utility. The file transfer time from the mkIII to my
MacBook (2.16 ghz/2 gig ram) went from around 6 seconds with the MacOS to about 2
seconds with Windows xp. Much more importantly however I could easily shoot 15 plus
images rapidly before the buffer hit and when it does the camera captures do not come to
a halt as with the MacOS but cleared quickly, incrementally, and allowed for more
shooting.
The handling, capture speed, data transfer seems very similar to how the mkII worked
with the same laptop with the MacOS and Fire Wire
So in my opinion mkIII/DPP/USB 2/tethered and the MacOS are basically not compatible
with shooting any action basically due to Canon's use of USB 2 and Apple's poor USB driver
speed.
But with a Windows laptop or with an Intel/Mac machine with Boot Camp the capture
speed and buffer seems robust. I have not tried the other Mac VM programs Fusions or
Parallels. These allow you to run both Mac and Windows at the same time (my
understanding is that Fusions might be better for this). It would seem that these may be a
little slower with more memory overhead but I'm not sure.
The bad news here is if you have a Mac you have to upgrade Leopard, and/or get Fusion, buy Windows, and fuss around with all that entails. The good news if you have a Mac/Intel at least you can take advantage of this new camera in the tethered mode and shoot action.