btw afa the AutoCopy in Opera goes.. the best of both worlds is the way it's done in ClickCutter AutoCopy AddOn for Firefox. If you select with the mouse and hold down the mouse button for the trigger duration, a little (c) pops up to let you know it was copied to the clipboard.
I found it too difficult to tune the duration so that I could easily avoid the copy with the mouse. But I found that if you select with the keyboard, it does not try to autocopy. If you want to select text with no chance of it autocopying, just use the keyboard. It really works well. I find if I'm off by one character I just keep moving the mouse and it periodically updates showing the (c) so you know when you have exactly the portion of the line you want in the clipboard. Very nice.
Something like that should eliminate the paranoia for those who hate to autocopy by accident.