One last word. I would like to say, that I don't feel Ultimate SEO URLs or Simple SEO URL to be a competitive product to MSU.
Unlike MSU both are using internal Zen Cart API - it has positives and also some negatives. MSU is not using internal Zen Cart API and it also has positives and negatives (yes, MSU is not perfect too).

Also, it is good to see there is active development for completely free and open source add-on. MSU is closed because contains proprietary techniques which were developed separately and are used in number of different products (some you can see on our web site and some are also made as compete customizations to web site engines).