Useful, but difficult (until...) Rated 3 out of 5 stars
This isn't the most intuitive add-on i've played with, in fact, I couldn't get it to work AT ALL until I used a feature in another add-on called Aardvark (http://www.karmatics.com/aardvark). Sadly, Aardvark doesn't appear to be a Mozilla approved add-on, but works well nonetheless.
Aardvark allows you to highlight parts of a page by "html element", and pressing the "K" key will add a filter for you for RIP.
If I hadn't noticed the option in Aardvark supporting RIP this would have been a waste of time for me.