I've got an iPod Photo and the camera connector. Haven't used it even once in the field. I think its painfully slow, esp if you have a reasonably large CF card like 1GB. Like someone else mentioned, it really drains the batteries quickly. Plus, if you don't have a card reader to plug to it, you will have to plug your camera to it and wait for ages while it copies and won't be able to take pictures in the meantime.
I've got a Vosonic Xdrive 3320 as my photo backup drive and its heaps faster and much more practical. I'd recommend getting something like that and leave your iPod for music. There are a lot of choices now for decent prices.
I don't consider myself a heavy shooter, but when shooting RAW or an important event I quickly run out of CF space (unless you have heaps of CFs) and dumping it quickly to a drive is important, so you can keep shooting. No way you can do that with an iPod. I've survived photo-frenzies (like my sister's graduation) where I was taking pics like crazy for most of the day with only a 1GB and a 256MB CF card thanks to the Xdrive. Just swap them out when one is full, and offload one card to the drive while shooting with the other.
