I never actually saw an ES fitting, until a GLS downlight hit town,
ES fittings used to be very rare in domestic fittings here, although you'd find them employed for higher-power spots, theatre lights etc.
The ES fitting for regular GLS 60 and 100W fixtures has become much more common in recent years with fittings sold right across Europe, but the BC type still reigns supreme. Many people here look upon ES bulbs as "those funny types."
The only real advantage I can see to BC over ES is that you don't have to worry about polarity -- A minor point.
