I am very thankful for this plugin, it does something (which I find) very important; keeping a well organized structure on your site in permalinks.
However, in my experience this is a very heavy plugin. The sites on which I run this plugin are obviously slower than others, esspecially when there are a lot of custom posts. This probably has to do with all the rewrite stuff going on. Do others have the same experience and maybe solutions?
But I wonder, why isn't this feature in the normal WordPress? Did you spoke with WordPress developers about this, plugin author?