Hey,
the document approach would not be suitable in your case i think.
In my case i would have a list of 1-500 entries ( 99% below 50). This listing-document needs to be re-written to the Database every time the user inserts a new thing or removes one. In your case the listing would need to be rewritten every time a new user is created or removed.
If you ‘have lot of users’ managing a listing-document would not be a good approach. You should use the views and possibly query range-based ( user:0 to user:1 … user:a to user:b ) if you run into problems.
And you might think about if the ‘stale=false’ setting is necessary in your case. This setting increases the query-time a lot.
However i did not change my setup by now. I’m still using views because i’m using a better machine and the serverload is globally still pretty low.