I have several of this type or ring dice ... I suppose I should included them on the site ... The ones I have do freewheel well enough to be randomizers ... what they lack is the arrow pointing to a specific outcome ... which the kickstarter seems to have :)
Truth ... I seldom focus on use ... but now that you mention it ... I have not seen too many other (non D&D) game systems that use d12's ... I know Button Men does ... in addition ... they are excellent for determining time of day ... when used with another die to indicate AM/PM (assuming a 24 hour day of course)