The idea for this mod appeared some long time ago when I was playing my own modpack which followed Forgecraft 3 idea of no OP features like EnderStorage chests or tanks, Mystcraft portals etc. And one problem that stood before me was placing reliable railways to distant places using Nether as shortcut. As you might know, vanilla portals are a bit hard to predict where cart would go out of portal. The other problem was ridiculous amount of cooldown. AFAIR Direwolf20 used complicated contraption which was picking up and then re-placing carts.
Anyway I thought it to be kind of working around inherently faulty mechanic. So I devised this mod as a better replacement for vanilla portals. Mine should've been more predictable in both where they spawn and how entities travel through them. At some point this idea evolved into a full-fledged inter-dimensional transport system, which is not overpowered like many portal mods are, but isn't ridiculously hard to setup, like IndustrialCraft teleporters.
The result is this mod.
Enjoy.