The difference is ... Presto itself could never use more than one core on a multicore processor. If you have a quad core system, Opera 11 itself never uses more than 25% (and possibly another process for plugins). I'm not sure you can even find a current system with a single core processor. But also, if one process gets hung up everything else will continue to work. But there is overhead involved - both in RAM and speed - with multiple processes as well, and if you were running on a single core processor Presto would blast Blink "out of the water".
you can find further customizations at opera:flags and in opera:settings after activating power user settings (Konami code).
Importing unfortunately isn't possible yet.
Why do Opera keep removing all the features that made it better than the others? I've been using F12 daily, although it did get less useful when I couldn't toggle java and flash separately anymore. How am I now supposed to toggle addons on for sites that need it and off for sites where it's a nuisance?
Only things left is one-key shortcuts. If they go, or Firefox starts implementing them, I'll switch in a moment.