I anticipate having similar issues as I am about to give up tape completely as I hope to get my PMW-350 next week, I have been using an EX1 for nearly two years but have rarely needed to ship footage. On occasions I have burnt the data to a dual layer dvd, but this is a bit slow.
Have you considered using SD cards to transfer the data between you and your client. Cheaper than SxS cards and as you would only be using them for data transfer you would not necessarily need the most expensive option. Easy to transfer to an SD card and hard drive simultaneously using Shot Put Pro so everything would be backed up safely prior to shipping.
Mark
London Stock Footage
High Definition stock video shots of the United Kingdom’s capital city