Yes, you can simply swap Slim for Slim Plus since they were basically the same template with the “regular” Slim did not support search and pagination. The discontinuation of Slim and Tile were to better unify the feature sets across the templates.
The category shortcode option is actually one of the core options available to all templates, even the free ones. Maybe I should update the docs stating that you can use the template specific options alongside the core options too.
Thanks for your time and valuable feedback!