1. FXP you can use a client like flashfxp or FTPrush load both seedboxes on the ftp client and just select what you want to move and transfer 

2.  Resilio Sync as long as both seedboxs support this app  just install set up and link pick the folders you want moved and it will do the job for you 

3. SSH  below is a guide to move from one seedit4me seedbox to another  ( if moving to another provider you will need the there SSH information )

To transfer files between two seedboxes you can use the 'SCP' command from an SSH connection. Our boxes will let you use this command to transfer data from another provider as well.

Transfer files from one Seedit4.me slot to another Seedit4.me slot

To begin you need to first enable SSH on the slot you want to copy file from. Once that is done you can connect to that slot via SSH. After that you need to navigate into the directory you want to copy the data from and then use the following command (assuming you want to copy the files to the rtorrent download directory):
scp -r -P PORT seedit4me@SERVER.seedit4.me:remote-source-directory local/directory

Replace port 'PORT' with the SSH port number and 'SERVER' with the server identifier you want to copy files to. So for example:
scp -r -P 2367 seedit4me@gsb3.seedit4.me:torrents/Movie-name/ local/Movie-name

Transfer files from another provider slot to a Seedit4.me slot

The same basics apply here, but you need to figure out how to access your other seedbox's SSH connection. Once you've done that, you can simply use the same SCP command as above.