A proposal on how to IMPLEMENT faster rails (for the Minecart Update)

I understand that the developers are reluctant to update the speed of minecarts because that would break many redstone builds that rely on the current speed of the minecart, and I also understand that simply adding copper rails and making those faster would not make much sense because gold rails are more expensive and therefore they should be the better ones.

So here is my proposal to solve this issue:

1) Replace all gold rails with copper rails. Change the texture, the name, and the crafting recipe, but not the functionality. A player who updates their world will have all the gold rails they have be replaced with copper rails, which will have the exact functionality of the previous gold rails, which means this change will not break their machines. (But, if possible, do make sure that these copper rails can revert to gold rails upon a downgrade).

2) Re-add the golden rails. They are now the better rails.

3) Aside from making them much faster, here is what I think they should function:

The speed of a gold rail should be determined by the redstone power level it receives. No power level functions like a brake (just like current rails), a power level of 1 can be turtle speed, ~5 can be copper rail speed, and a power level of 15 can be blue ice boat speed (or faster, since there should be a good incentive to build railways).

The copper rails would function exactly as present gold rails; their speed will be consistent regardless of redstone power level (other than 0).