I've been looking for an answer to this myself to prep for an upgrade, and was thinking I might try Macrium. Since the OP never responded on whether or not the suggestion worked I'll give it a go and report back tonight or tomorrow.
First Edit: I'm presently cloning the drive with Macrium. My first impression is that it is slow. I've been running the process for 30 minutes and have progressed to 1% of the cloning. As backdrop, my primary XBox One external HDD that I'm cloning from is a 5,400 RPM 1TB Toshiba at approximately 70% capacity. My target drive is a 7,200 RPM HGST 1TB. Perhaps things will speed up, but at this point my impression is that a person would be better off just transferring data between drives using the Xbox One's interface. I know transferring content from the internal drive to the external drives is relatively quick given the size of games. I was hopeful this option would be even faster but at present it is not shaping up to be the case.
Second Edit: Two hours later, and Macrium Reflect is at 13%. Both drives are on USB 3.0 connections, and I have cloned other 1TB disks completely in approximately one half of the time. I'm cancelling at this point and just leaving this as a "not worth it" option as the Xbox interface I know will produce the same results much faster.