I understand you regarding buttons, but one thing is not quite clear... I really don't see any sign of 3D in those buttons except that diagonal cut-off on one corner. I thought, you want to have sharp square instead ot those on the screenshot. Buttons are single coloured with just one additional color and that's orange, from the web site.
On-Demand and On-Access buttons would be nice to have, but unfortunately, if you try to "dig" little bit in SkinBuilder, you'll find that there is nothing that will point us what are those functions for specific buttons. We can't see where is the link between buttons and that particular function inside the code... if there is something like that, sure we could use those information and try to make something like that, but until then... I don't know...
Another thing, keeps bugging me... if we add those buttons, and then by pressing let's say On-Demand button, we invoke showing of those additional 3 buttons (Local Disks/Removal media/Folders) it doesn't sound like shortcut... so I'm sure we'll have many people complaining about that. Before they had those 3 buttons in front of them, ready for action, but this way, they would be forced to press On-Demand button first, and then one of those 3 buttons...