Shorter is quieter. And switchblocks are unnecessary.
Disagree on both counts.
Shorter is most certainly louder. That is common knowledge. The noveske switchblock also works very well. I was skeptical at first until I actually used one. It greatly reduces gassing to a more normal unsuppressed level when shooting suppressed. You can also shut off the gas with it for the quietest shots. I don't run one on my gun only because of the rail that I want to use doesn't allow it.