The way I use FARR's directory search feature is if for example I need an application/folder in program files but it's not in the start menu, or running a utility that doesn't come with an installer (my utility folder is too big to be included by default in farr searching): i'd do c:\scr\auto to get to c:\scripts\autoruns\ for example.
Although it seems if i type 'auto\' without quotes, it finds folders in program files even though program files is not enabled in the searchable folders hmm.
However pressing F7 and typing auto is faster. And as the results are indexed, it doesn't have to search the actual folders, just the indexed file. it's slightly more convenient. I don't have to worry where the folder is (c:\, d:\, 12 subfolders deep). So it's mostly a matter of shorter syntax and slightly quicker performance.
I guess when FARR adds in indexing, or some syntax shortcut so I could type '\auto' to search folders with the phrase auto in them, then I might dump Folderscout
Also I use a dialogue box extender which works well for favourite folders. I hope that explains things a bit?