what about search terms?
Anyway, I'll give it a try if you want, but I don't have the sister plugin.

BTW, I can guarantee that I some of the most targeted traffic in the world. My niche is so specific that not one of all the visitors I have had have been accidental. My site is the only of it's kind. If you want a link to my site, I will give it to you and you will agree.
Could be a cool test subject for your plugin.