this is just speculation.
i agree a supercharger is more "even" in delivering power.
and once the turbo spools, it keeps spooling. the more you give it gas the faster the engine shoots out exhaust, which turns the turbo.
so the more you use the skinny peddle the faster the turbo spools as the rpms rise..
but it all varies in different setups. depending on the size of turbo used and what not
And that is why you need a correctly sized turbo.
At some point the exhaust side of the turbo will get "backed up" and power stop building as rapidly with RPM because the exhaust gases can't escape through the hot side of the turbo quickly enough.
Also people think "OMG 20psi awesomezors!!" and they're idiots.
PSI = a measurement of restriction.
If you bolt on a decent turbo and build say 8psi at 3000rpms(for examples sake)... then you port the heads and/or install a larger A/R exhaust housing on the turbo(A/R = cross sectional area ratio) you may be building 6psi at 3000rpms now... but you'll be making more power.
8psi may be 100CFM going through a 0.48" A/R housing
6psi could be 130CFM going through a 0.60" A/R housing.
Since the housing is larger... more air can pass through at a given time at the same or lower pressure.
It's not boost that makes power... it's AIRFLOW!
And that misconception is why everyone is generally retarded when they talk about turbos
Also, you need to look at turbos and their compressor "maps" and know how to read them so you can stay in the range where they are efficient. At some point in all turbos they will become "efficient" as they get enough exhaust flow for a given engine size and exhaust housing. Also at a later point they will start building heat and become inefficient because they start building more and more pressure(which adds exhaust backpressure = strain) and all it will do is become stupidly H-O-T air. They get to a point where the intake air isn't supplying enough CFM to adequately get through the motor fast enough to pump on the exhaust side of the turbine to make more power.