Rated 3 out of 5 stars
This is a brilliant idea, and in my opinion should be engineered directly into Mozilla Firefox alongside whatever functionality https://addons.mozilla.org/en-US/firefox/addon/suspend-background-tabs/ brings to the table. Firefox is a cumbersome bundle of uselessness the moment one opens more than a half-dozen tabs, and these add-ons definitely help.
Alas, this add-on has some very significant flaws which make it (for now) unusable. Specifically, the renaming of retired to "data:text/html…xyz&l;/title>". If this can be fixed and/or retired status be signified with some sort of on tab emblem iconography (a'la TabMix Plus tab protection and reload features), this little add-on would get 5 stars from me.
Is this add-on still under active development?