Maybe lower power states would reduce cart acceleration as well?
aye, that would be redundant for you would need power rails in front of the lowered power rail in order for that to happen and by the time you have reached the powered rail that is barely powered. you are going at top speed.
The only way to make that possible is if the streangth of the powered rail is the same as what the strength is of the redstone that is powering it from.
all in all though, a nice look and feel change. i like it