Fastest way to move or copy files on the ReadyNAS?

I recently bought a ReadyNAS Duo V2 and loaded it with 2x2tb drives. I then took on the task of moving all my media from my external 3tb to it. Since I found out it does not recognize hdd greater than 2tb I'm moving data 1tb at a time via another external 1tb usb 2.0 drive I have.
After starting by copying from one share to another on my computer and realizing this is bringing the file from the usb at the nas back to my computer and then back to the nas, way too slow for the approx 3tb of data I have to move. SSH would be the way...

I have fully updated my NAS firmware to 4.1.10.
I've enabled SSH and installed PHP 5 on my ReadyNas Duo V2

I tried this:
Extplorer addon but it fails every time I try to move or copy a file; checking share permissions, the share should be wide open.....
FileZilla client from my pc and while I can make a SFTP connection and get root access, again, any file move fails. I have to blame this on some sort of access from the FTP to the share but I've checked and double checked and can't figure it out. Same thing with WinSCP client from my pc
Same failure issue with the ExploreBoard addon

Here is what is working for me now:
I make a PuTTY connection to my NAS with root SSH access. I then use the mv command to move a file or directory where I want, ie: Movies.
PuTTY stops responding at that point (it will come back if you leave it open once the move is complete) so you don't really know if it is doing anything, but if I get up and go over to the NAS and external USB both have lights blinking indicating data is being moved.
Then I launch Beyond Compare on my pc and enter the original location on the left and the new NAS location on the right, showing me the files at both locations. I use F5 to refresh the view showing the data growing on the right. A final compare afterwards of another location that contains a full copy of the files I'm moving ensures me all the data has moved entirely as no differences are shown.

Seems crazy this is what I have to do but, I know, but hey it works and pretty flawlessly once you get the hang of it. I know I could probably get WinSCP or the other apps but after trying for so long I've given up...maybe one day I'll give em another crack. If anyone knows what I may have been doing wrong, please do not hesitate to let me know!

Thanks for all the info from this post!

I still don't get why it says the rnd2110 can hold a maximum of 6tb on this page - http://www.netgear.com/home/products/storage/prosumer/rnd2110.aspx#two but come to find out it cannot....someone please update this info or make it more clear...and yes I do see that it says 2x2tb...conflicting info? just seems unclear....