I really like the Triangular grid idea. That seems like a good compromise between a 7 segment display which looks really bad, and a graphics display that normally cost way too much. Yes a reasonable set of fonts will need to be tested against the layout before it is frozen, but I think it will yield the best compromise. Given that most rendering engines work in terms of triangles it makes al ot of sense. We will need to develop the right set of primitives in a library for driving it, but there are plenty of places to beg, borrow, or copy the algorithms.
The decision will come down to number of triangles to cost clearly if you choose to go this way, how small will they need to be to render non roman characters, in a reasonable form? Line drawing and other shapes are well defined in triangles, and as an earlier post a polygon can always be decomposed into a set of triangles.