Rated 4 out of 5 stars
Works, and does what it promises. Good replacement for BarTab, doesn't have the problems Bartab has since FF 4.0 (some pages don't load).
Caveeat: if you decide to disable it - your session may be lost. So, maybe you should activate all tabs before saving the session (didn't tried it)
1) The settings in about:config should be created by addon itself.
2) Selective tab unloading, possibility to have some tabs (the interactive ones) always loaded.
Comparing to Memory Fox - works faster and frees more RAM. I don't know why, maybe because of Memory Fox somewhat ineffective swap file usage.