I use my browser as a reading list as well. And I like it.
I have had epic browser sessions with more than 500 tabs, until I discovered the Max Tabs extension, that let's you set a max limit. I use 100 now.
The extension Bartab Heavy lets you load only current page on start and automatically unloads tabs after x amount time. Otherwise 500 tabs wouldn't be possible.
Furthermore I use Tree Style Tab extension, that put them on the left side. I got used to this in Opera. Still miss the Ctrl + Tab (IIRC) feature, that only showed the list when you tabbed trough them akin to Windows' Alt-Tab window.
The existence of these extensions sooths me a bit since it means I am not the only one with these bad habbits.
Good to see Opera still attracks new users.