In the previous post about Joomla, I listed some extensions that address the category limitation issue. However, installing third party extensions runs into the issue of updating your original CMS software. Before you decide to expose your Joomla site to the Update Dislocation Blues, you might want to look at the upcoming 1.6 release.
http://developer.joomla.org/coordinator-blog/304-joomla-16-alpha-2-released.html
New improvements/features since alpha 1 include:
- ACL: access management for global permissions as well as content item specific permissions, variable usergroups, users member of more than one usergroup, permissions are inherited, really fast
- Extendable user profile, profile view in frontend, extendable user parameters
- Tableless com_content layouts
- Improved com_content modules (mod_articles_archive, mod_articles_latest, mod_articles_popular)
- Article linker plugin for editors
Other Joomla 1.6 improvements that existed in alpha 1:
- * Nested Categories and category parameters
- New views in frontend: categories, category
If your Joomla site was extensive enough to run into the category limitation issues, then before you try to marry Joomla to K2 or one of the other programs, it might be worth the effort to download the 1.6 alpha and try it out to see if it will address your issues. It does require a test site with PHP 5.2, and while the update is not ready for production, if the new version improvements will keep your site within the Joomla core, it might be worth waiting for it.