I have 2 sugestions missing in your great plugin:
1. Alowing to keep the serach field typed keywords when the user clicking on result, and then click “Back” on his browser.
2. To alow Admin to create synonym for search keywords that will give results if a user is searching a word that exist in Admin settings, and its synonym if fiund in one (or more) of the Posts/Pages. I.e: Typing “Pet” in search will show a result in an page that has “Animal” keyword and a synonym in Admin Pet=Animal.