There is already an item about retaining sort options for dates so I'll make sure this is appended to it.
The main problem with this feature is that results are not smoothly added to the bottom but are constantly inserted throughout the list as rows are inserted at their proper sort adjusted locations, which can be a little disorientating if you're working with the results while the search is still running. However, this has been requested several times so it's moving up the Issue Tracker priority rankings.