Wow, Vinik, that's some awesome info there! And those templates are amazing! I had to painstakingly create mine from scratch after working out what all the combinations were. Having it all laid out like that is really useful.
As I understand it, if your tiles have reflective symmetry (like they seem to do here) then (if you ignore slopes) you should be able to use the 16 piece tileset. Each tile is just half the length and width of the full tile size you want to use. The 16 piece set contains everything you need - inside corners, edges, outside corners, inside pieces. This means you're using less memory, and far fewer rules in your rule tile.
This doesn't tend to work as well for more complex or organic tile patterns (rocks, leaves etc.) as things like shading and variation can stop things looking good when made out of such small tiles.
The tile download is interesting too. It uses a less geometrically perfect triangle pattern with a random element added to the triangle widths and heights. That means that it's always possible to join up corners and edges - you can carry on the diagonal, or swap its direction and the pattern still works.
I tend to work with more organic textures, so when I need to match up to the next edge or corner I'll just work whatever I get into the design. Create new leaves, make a wide rock, that kind of thing. To a certain extent, by making the patterns so regular you're making life really difficult for yourself. Adding slopes into the mix was, in retrospect, a very brave thing to do.
