Unfortunately, all I seem to be able to do is use the --location-autofill=nearest option. So I don't seem to be able to take advantage of the new improvements. I did create preprocessed .bnd files using the --createboundsfile option on my 6*obm.pbf files, but then using --location-autofill (defaulting to the latterly created bounds directory) does not produce a searchable map on Basecamp or GPS. Perhaps this is explained by the admin boundary status at
http://wiki.openstreetmap.org/wiki/Admin_level#admin_level