Whatever you do, don't rename your custom post type's slug to something with a lot of characters.
I renamed mine and all my posts disappeared from my site. (!) I checked the database using phpMyAdmin and they were still there. It took me some searching to see that the new slug I had given them had been truncated so that was why they weren't appearing. (Apparently there is a 20 character limit? At least in my setup.) To fix it I had to rename the slug to the truncated version (in the Types admin interface), and then rename it again to something shorter.
So a nice feature would be to prevent the user entering slugs that are too long and will be truncated by the database, or to truncate them in Types so that the two don't get out of sync like this.
Just thought I'd share my mishap. Thanks for a well-done plugin.