External Storage Capacity for 411slim

[csm]

I realize the internal storage capacity maxes out at 4TB. Is there a maximum external storage capacity for the 411slim? I like everything about the 411slim, and I imagine it will suffice my storage needs. However, I'd like to know if I can expand storage, and if so, by how much and still have the device function properly.

Has anyone attempted to expand storage externally? If so, what setup are you using?