How to copy files from EX4 to PR4100

Having access difficulties with my EX4 (which I am told is now end of life and for which support is practically zero despite having raised the issue with tech support over 12 months) I had thought to buy a PR4100 shell and simply transfer my drives. Tech support say this will not work and I will have to format my drives thus losing 3TB of data. These are a hot swappable Raid 5 group of 4x3TB drives (12TB) and I find that response not very helpful. The other option would be to buy a PR4100 with drives and to copy from one to the other. I am told I cannot do this via the USB but must do it over the Ethernet network again back to the access issue (currently 10 minutes to read or store a 512kb file). Any thoughts?