Welcome to the forum DR650SE. One thing I have often wondered if I have a 30GB iPod Video and convert to a CF/SSD of 64GB. Using the original firmware if you then try to sync more than 30GBs won't iTunes stop the transfer when it gets to 31GB because the firmware in the player says I only have a 30GB drive or are Apple devices free of these kind of restrictions ?
I don't know about sync, but I have replaced a 30GB HDD with a 128GB CF. Both Apple original firmware and Rockbox recognize it as 120GB capacity. I was able to load it with the 120GB's using Rockbox.