Bought the soap and the EdT. Already owned the old Tabac-hard-soap-formulation of Fine American Blend and the matching aftershave, as well as a decant of the actual YSL Rive Gauche pour Homme.
Seine Reserve is Very close to the drydown of "La Collection"-era Rive Gauche, albeit without the original's faintly citric opening. The soap and fragrance smell essentially the same. Fragrance has decent strength and long staying power for a Stirling dupe.
As a point of comparison, FAB soap is slightly cooler / greyer / more anisic in character (in a pleasant way, a little like Gillette Foamy), FAB aftershave is a little more medicinal (in an Acceptable way), and FAB fragrance is not recommended. If you can track down the vintage hard-puck version of Fine American Blend I'd say it's worth trying; if you can't, I'd recommend this Stirling version instead.