“however it seems that there isn’t a way to turn off the feature”

I don’t think so.. even if you are logged in the search result seems (to me) to be the normal one. When you are willing to see the notes you go to “See all notes for this SearchWiki”. So you know what you are doing. And if you are in the “See all notes for this SearchWiki” yes there is no direct way to get back except the browser back button… but indirectly you can go through “Google home” listed at the very bottom of the page. But this time you have to search it again. I think google should implement the ‘all notes view’ with the paging system(1 2 3 Next page etc.) together with top and bottom search fields of normal search.

The question of how much usable this feature is to me… I don’t think much.. for I am quite satisfied with present search. I usually get my desired results within first 10 in the list. For off bit topics where I need to go through the several pages of google search listing might be benefited from the user inputs. Let us see what google does in this regard.
To me I might find the feature “See all my SearchWiki notes” useful in days to come for what I think now that this might be my ‘Bookmarks Online’ once I get used-to with this.