Yes but it is still FTPing using the UnleashX's built in File Manager FTP client. Essentially it works just like the File Manager does normally except the right hand pane is another Xbox.
Connect the two Xboxes using a cross-over cable and make sure they're both set to Static addresses and have different IPs ie. primary Xbox set to the default 192.168.0.2 and the other 192.168.0.3. Turn both on and use the UnleashX dash which can be either as your main dash or installed as an app.
Go to the UX File Manager and use the White button context menu. Scroll down to the use FTP option and enable that. In the right hand pane you'll need to set up a new connection so name it and put in the details ie. the IP address of the other Xbox and save. Use it and it should connect and show all the other Xbox's drive folders.
You can browse through either Xbox's content just shift between the two panes using the left and right triggers. The FTP transfer menu is again found using the White button and works very much like using the UX File Manager to copy between two locations on the same Xbox. Once you click Transfer it will start immediately.
Positives:-
It works better than any other method, at least any practical one. The Xbox FTPClient application you can find is a poor alternative with a lousy GUI and hideous control system.
The speed of transfer is reasonable but do not expect it to be PC fast.
Disconnects are not unknown but in my experience far less than when FTPing to a Xbox from PC.
If you're used to the UnleashX File Manager's GUI, which IMHO is as good as it gets, you'll take to it like a duck to water.
Negatives:-
The progress bar is all but useless.
The UnleashX File Manager has a few quirks - it does not like anything it recognises as a text file but has no recognised extensions. It is fine with .txt, .nfo, .xml, .cfg and maybe some others but anything else without an extension and the transfer will stop with an error. Unfortunately a lot of XBMC installs with Python script stuff and some plugins do contain such files typically the README and CHANGE (Changelog). Emulator content also may include similar problem text files too.
My theory is that these files are OK if you used a XBMC main dash when FTPing from a PC because that has a built in file parser but you're now running on UnleashX dash/File Manager rules. So despite it being a transfer from one Xbox to another you do get this annoying little problem.
It is easily fixed by checking in the provided error log and if it is a text file issue, finding it and giving the file an UX friendly extension. It should transfer then no trouble. However possibly having to do that multiple times and then restart the transfer again gets tiresome very quickly.
Hope this helps.