One gotcha with the older MK II bodies is the lack of support for 64 bit pc operating systems. You can use the USB port to download images, but you must use the firewire port when you want to do remote release or change some of the settings that are available by no other method, so you will need to keep the original software disk with windows XP 32 bit drivers for the firewire port. That has frustrated many new owners.
I'd say go for a 1D MK III which is well supported, even though the MK IIN is a great camera.
Good point with the support. But all I ever hook up for is to sync date & time between 4 different bodies.
Downloading is fine by USB but most people will probably choose a card reader.
If you do go for a Mk3, try to get one that is a late build...the frustrating earlier issues were evidently sorted towards the end.
Canon did do hardware fixes to 1000's of earlier Mk3 bodies.