I think I've read somewhere that it's possible to run trains of steel rails really fast, but doing so creates lots of wear, so it would not be economical to do it routinely. That the big advantage of the maglev technology is not the absolute top speed, but the fact that the maintenance is cheap even at high speeds.
But it has to be economical: if the cost of wear over the life time of the system is less than the initial cost of building maglev, then you're still ahead.
