I finally found a fast, large hard drive that appears to work properly in the UDMA, the Hitachi Travelstar 7k1000. I believe this is the first (and currently only) 1TB 7200 RPM laptop drive of the standard 9.5mm height. I need to perform full testing over the next few days, so don't blame me if there is a compatibility issue not easily evident.
Hopefully the original poster found a solution for the safari.
I was looking for a similar device, but never was able justify the high cost vs. getting more cards. I ended up using the USB-OTG (on the go) functionality in my phone to copy files from a card reader to an external hard drive.
The solution is not as elegant as a single box device (in fact, there are cables everywhere) and requires external power, but it does allow me to make a backup in those situations where I don't have a computer. It does have a lot of prerequisites and a bit of know-how, but maybe it'll give someone some ideas.
The basic idea is that the hard drive and card readers are connected to a USB hub which is connected to the phone via a USB-OTG cable. The USB hub will need to be powered for the hard drive and the card reader; I was able to drive everything off of the hard drive power. Once the devices are connected and powered on, the actual file copy is done in the phone with a file manager. The speeds were fairly fast, but still took around 10 minutes or so to transfer 16GB.
I'll admit that there were a lot of pieces that had to align perfectly in order for this to happen, most notably already having all of the components on hand. If I didn't have any of the parts, I probably would have just bought a ton of cards and kept them safe.
