Yes, there should be no problem and your data is maintained. I would back up your site if you have any concerns since I am not sure what versions of WP, PHP, etc you are using and it is just a good idea before making any updates especially on a live site.
Here is an instructional page about upgrading the base plugin and then the add-ons. Before you download the EXP add-on file, you will want to deactivate the Enhanced Results, and once you have EXP activated delete Enhanced Results. Its been a while since I had any of the Legacy add-ons on my own site. I think they will be deactivated anyway but to be sure I would deactivate it first since it isn’t working for you at this time.