Sortable 'date' columns in tabular collection results in 4.3

The table_sorter.js expects a class of 'sortabledata-*' otherwise it tries to sort the column alphabetically - not so useful with dates, especially when they may be in the US month-first format.
As the template in already has a special case for Dates I'm suggesting it also add a class along the lines of 'sortabledata-20160726'.
I am aware this only works on the page of results shown, the use-case we're coming across doesn't paginate the results anyway.

Would this be the best way to go about this? Should the time be included as well or is that potentially going to complicate things?

You want a 'data-' attribute for this, not a dedicated class for each value.
In general: sorting by the contents of a table is often broken since a table may contain unrelated markup.
But if you really need a powerful table/grid implementation then you would look into, JSGrid or agGrid (my favorite). The out-of-the-box functionality of Plone here is too old, too simple, too weak, not very much usable in reality.