Q: Will all smokes learned into the system sound when one goes into alarm?
Q: Yes with no programming required. It automatically work that way for the one-sound all-sound setup on any of the panels that they are supported on (DSC Neo, DSC Pro or the Qolsys IQ2+/4.

One benefit the Qolsys panel has with the PowerG smoke/heat detectors, is that there is a programming setting that you can enable to make all of the PowerG smoke/heat detectors act as additional sirens on a burglary alarm system.