Worth backing up large files?

You can transfer your domain from one server to another server using the inbuilt tool of WHM --> Copy an account from another server.

 

This process requires the root password to their server. If you do not have root access to that server (for example, if you are a reseller) then it is unlikely that they would provide that information.

One thing you could do is generate a full backup and have their server FTP (or SCP) the full backup file to your new server. You can then move this file to /home on the new server and use the Restore a cpmove file feature in WHM to create this account on your new server and restore the backup. This assumes you have root access to your new server.

A lesser efficient option, but one I personally use, is generating a full backup in cPanel then downloading that backup to my workstation. Then I upload that backup to the new server, move it to /home and restore it via WHM. This leaves me with a copy on my workstation in case my main backups somehow become corrupted when they're needed, I still have one copy of the site available to extract what I need.

 

I would use the same technique but initiate a client to client FTP connection
and directly transfer the full backup archive from the Cpanel account to the new server without the intermediary step of downloading the file. Basically operates like to simultaneous bridged FTP connections.

For those who don't know how to do that or if you are completely cutoff
from FTP including even client access, you could move the archive file into your web space and just wget it from the new server. Once transferred, you can move it to /home and run the cp restore tools.