Well you just plug in the USB cable and the PC sees it as a drive. Also you can play files directly from one or more of the thumb drives without loading to HD. As you know with the Roland you had to put everything in a special folder without option to use subfolders. The new Ketron system is very similar to the later Yamahas in this regard.
As to OTS, as used by Yamaha and Roland, Ketron has none preset from the factory. It does have numerous Programs for each voice bank and you can build your own or use a voice list in which you can store sounds or programs. It also has a second Registration system (Block as opposed to Single) which allows instant access to most anything you want to put there, on one page.
I much prefer the directory system on Audya.
Too many banks and layers on Yamaha, at least for the way I use it, which is of course what matters to me.
You can't compare the new OS on Audya to any of the older Ketron systems. It is a totally new approach. The Midjay came closest to it.
DonM