ReadyNAS 4200 Compatability with 10Gbase-T Copper Card?

Hello, we have an older ReadyNAS 4200 unit. We currently own the 10GB SFP Module; however, we are re-provisioning the unit and it will require a 10GB RJ-45 Copper connection to our Dell 10GB Copper switches. (4 x SFP ports are already used up to create a "stack" between the two switches)

According to readynas support there is no official card support; however, have any of you had any luck with a 10GB Copper card in the past that we could try out?

This is the card I am looking at purchasing.

Intel E10G42BT X520-T2 10Gigabit Ethernet Card 10Gbps PCI Express x8 2 x RJ45

http://www.newegg.com/Product/Product.aspx?Item=N82E16833106075


Any help would be greatly appreciated.

Thanks