Sorry, I do not know if any sites in the showcase are setup that way. There would actually be no way for me to know by looking at the site either.
The settings change only changes where Connections looks for its datatables in a WPMS install (oversimplified).
By default, each subsite would have its own set of datatables. With that option set in the wp-config.php file, all subsites use the same set of datatables. Other than than Connections will function identically.