Agreed that Turbo efficiency has been improving to the point that the low end isn't impacted nearly as much as it was even two years ago. A twin-scroll turbo routes the exhaust gasses from half of the cylinders into two inlet feeds, cutting down scroll time and making a more efficient design. This is not a standard yet - but is becoming more and more popular for both tuners and production cars. It's dangerous to make any generalization about any particular technology - there are exceptions to every rule and ways to lessen any negative performance characteristics which are specific to a particular type of engine application.
Smaller turbos scroll quickly. Sequential turbos (two different sizes) can cover the entire powerband. Twin scroll turbos bridge the gap between small and sequential setups. Turbos in general have more capability than superchargers and are more efficient, but come with their own set of pitfalls and are usually more expensive. It's always a balancing act between initial cost, performance, maintenance and capability (end goals of the user).