For example, can you search for keys or values in n-level nesting
Can do, as long as you can locate the location of the array containing subdocuments, you can search for what you want, can see my answer before:
http://segmentfault.com/q/1010000002943721/a-1020000003716002
If it does not meet your requirements, you can describe your problem in detail, such as what kind of data structure you imagine and what kind of search you want to do.