I'll also offer a +1 for this feature.
I put todo items in my notes and have a search that shows me a list of all notes with unchecked boxes.
I like being able to have my todos in the context of the meeting I'm taking notes on, for instance.
Or to have the todo in a note with all the related emails, web pages and comments that I'm gathered so far to carry out the todo action.
So I want to be able to search for notes with unchecked boxes ( I can do this) and then within the note search for the unchecked box to see the details of what I need to do next. Often a note where I record the outcomes of a recurring meeting will have many checked boxes for completed todos and a few unchecked boxes for the uncompleted ones. I'd like to be able to find the unchecked ones without scanning the note visually.