I'd just like to add, that AES-EBU is also balanced cable. Balanced cable is handy when transporting analogue signals, due to it's wonderfull noise cancelling properties.
Now start cancelling this noise on a digital signal!!!
AES-EBU is usually the select of the very rich, as it really *Really* keeps the digital signal clean from the standard crap. The cable itself isn't really all that expensive - what really costs are the converters required to take advantage of them.
at the end of the day, the actual factory price of the extra parts required really aren't that high. But, we all know that $1 in the factory ends up as $10 on top of the shop price - now multiply that accross each channel....
now you see one of the issues?
Cheers
R