> Firefox will respond by unloading memory-heavy but not actively used tabs.

A dropped tab cannot always be reloaded to the same content. No thanks, I'd rather get more RAM or swap space for paging.

The tabbing feature of "close all pages to the right of this one" is almost good enough for me.

What I would like is some UI where all the tabs are compactly shown as rows in a table. Here, you could select tabs and move them up or down, delete them, or farm them off to their own window.