To find missing data I use the custom report. Filter people born before and died after the given date. Then you can filter on the existence of some part of the information in the other category under source information. e.g. for 1841 census filter out if source information includes 1841 England Census. This seems to work, but you have to redo it after changes because the filters don't update dynamically. Currently there is no way of saving filters (this is something I would like to see). You can also use the filter on the people view so you can easily work down the list and find the relevant individuals.