I think tilted rings would also be a good idea.
They would open the possibility for complex and interesting looking system.
Generally I can imagine that US 2.0 could become very popular with the right amount of easy system customization abilities as well as tools for more complex systems. Thinking of it makes me always think of Garry's Mod for Valve Software's Source Engine. Garry's Mod basically allows the customer of it to perform very complex physics manipulation with objects based and made for the Source Engine. Since GMod allows you by this to build with objects there is this sort of automatic viral marketing effect which is going on websites like YouTube. People build up their scenaries or machines, are proud of it and show them to others on YouTube. Since however GMod also allows high levels customization there are also these kind of videos, in which people take a lot of time to make very complex setups but which are fun for everyone to watch. They build things like e.g. Rube Goldberg machines, Mechs, etc. These kind of videos have a very great potential for marketing since these will even grab the attention of people who didn't noticed GMod yet because they were not interested in it before.
Now US is not GMod. But both softwares have in common that they are played by allowing the user to manipulate the world. I think if the balancing act between complexity and simplicity turns out the the right way,
US will have big increase in purchasers and content-producing users.