keep in mind it just sorts by this value but more than one feature could have the same sort value and there could be large gaps in the values so changing it may have no effect if it still has a lower sort than other features it will still be at the top of the feature dropdown list.
The sort order in which features are setup on the setup page is not of importance for visitors nor editors of your site. The order in which those run is just the sort order of the feature folders at /Setup/applications/[featurefolder]
Though it will setup /Setup/applications/mojoportal-core before it runs setup for other features, so core features like Html, Site Statistics, Newsletter Sign Up, etc run first then it installs the external features in alphabetic file system order of the application folder names.
Hope that helps,
Joe