Redstone circuitry to change track direction is not a lag issue. The redstone gets activated or deactivated, and then it is done. It's not necessary to extend the redstone a very long way, if the circuitry is done properly.
I would much rather have this metro system in place rather than the /warp system, along with removing /home. That would create a real survival experience. However, I know people like having their home warps.
The metro thing would be really cool, though.