When I first heard about a big (compared to the Tyros line) USER drive I thought it would be the perfect replacement of the former hard disk. In fact, it's not. What is the difference?
The USER drive is structured as it always has been, the folder structure as given above (well, there was no hidden audiorec folder, because with the size limitation of the Tyros this didn't make any sense).
I'm not sure if the Tyros' hard disk was structured this way too, when it left the factory. My first Tyros was, because there was this SuperEdition giveaway stored on the hard disk and this was structured this way. So I followed this scheme for many years.
Now we come to the difference: with the USER drive you HAVE to follow this folder scheme, with the USB drive you MAY, but you DON'T HAVE TO. When storing/browsing registrations, the USER drive will always use the REGIST folder as the root (of course, you may create subfolders). The same is true for the other file types, styles, songs, multi-pads etc. In contrast, with a USB drive you may store a song in the REGIST and a registration bank in the SONG folder. Well, you might think I'm nuts, and of course this does not make sense, but I have something different in mind.
I like to keep things in a folder that are closely related. Think about your PC. Would it really make sense to store all your docs in a DOC folder, all spreadsheets in a XLS folder, all your PDFs in a PDF folder and so on? I think, when doing a project you would rather create a project folder and store all DOC, XLS, PDF and so on, related to this project in its project folder.
This is how I like to structure my Genos data in the future. The basic entity is the song. There will be a folder for each song. Everything related to this song, registration, style(s), song(s) (score midi file, mid/wav playback), multi-pad(s), whatever will be in this folder. I will even story copies of preset data used (style, multi pad, ...) into this folder. You may think this is a redundancy but it has an advantage. If I ever upgrade to Genos 2, 3, 4... the presets may be different, at a different location or just removed. Nevertheless my registrations will still work on a new Genos model as the links in the registrations will point to the legacy data in my song folder.
In the past this way of structuring data was not really feasible IMHO, because recalling registrations would require to much navigation through subfolders. With the playlist feature this is solved for me.
I'm not advocating this for everyone. I think if you have a large base to migrate from, you may be better off sticking to your approved scheme. I migrate from T3 to Genos and I find myself modifying each registration anyway, so for me it's the opportunity to change.
The USER drive still has a use as a repository. I will store all the styles, multi pads, songs, whatever I acquired over the years for quick and easy access. Here, the traditional structure makes sense for me. E.g., if you want to browse you repository to find a style that suits your needs you want to have all styles in the folder STYLE, possibly structured in subfolders reflecting the genre.