I don't know why but hearing about the sequential turbos being vacuum controlled seems so archaic?

Does the single turbo have a little bit more advanced technology and less vacuum lines?

 

You're talking about FDs/3rd gens? The twin turbo system has a complicated set of vacuum lines, solenoids, etc... to get them to run sequentially. One turbo does not need any of that. In most cases, the switch is to chase power goals that stock twins cannot obtain.

 

also, i heard the benefit is removal of the cast iron manifold? retains too much heat?