I know that it isn't politically correct, but long ago in the 80's, I read and heard that converters were not that beneficial to the environment. The chemicals which are produced by converters(instead of the popular emissions chemicals) are believed to be almost as bad. That's another debate like global warming. The chemicals which are used in the converters are not cheap or good for the environment either.
It's a lot like comparing the Toyota Prius to normal vehicles. It has already been shown that the Prius is a very bad vehicle for the environment. Its cost of production and damage to the environment to produce is worse than a Hummer. But that doesn't mean that the idea is unsound. The answer is to develop the technology into something positive.
The catalytic converter has been accepted since the 70's, and it's likely to remain unchanged(undeveloped) for a long time to come. Back on topic, please forgive my short rant.