The System Preferences approach probably doesn't work. It would allow one to reassign any normal menu shortcut to some other keys, but these bookmark entries (cmd-1,2,3..) don't have "menu title" in the way the normal menus have.
AskDifferent seems to have some advice on this (changing cmd-1,2,3.. to switch between tabs sounds like a no-brainer for Apple Safari GUI folks?). http://apple.stackexchange.com/questions/1621/how-can-i-make-safari-cmdnumber-sh ortcut-switch-tabs-instead-of-opening-the-boo
Apple, please consider changing the default mapping. Thanks!
As an added detail, which I failed to mention originally:
The "@" character is mapped in the European (at least Finnish/Swedish) keyboard layout as Alt-2. Meaning if one mispresses Cmd instead of Alt, BOOOOM one loses the open tab, gets a shortcut instead.
All my friends using Macs have faced this. And their friends using their macs face it as well - where did my tab go?
Compared to this annoyance and what-the-****-just-happened experience the benefits of being able to move to bookmarks 1..9 without touching the mouse are ... neglible.
At the least, give us a Safari Preference to turn this keyboard shortcutting off.
Quite frustrating to have the current page "overwritten" by a page from favorites, often losing a session or written form input. I ended up fixing this by emptying my favorites bar all together to another folder. I didn't use favorites anyways. From Safari Bookmarks -> Edit bookmarks, create a new folder, expand favorites, select all the favorites and cut+paste them into the new folder. No more annoying page switches..