Thanks.For silencing a weapon to be worthwhile, it needs to be something with a high alpha-damage so they die in one shot and don't have time to get their shields up.
I found a randomly audio-masked C-44 and got rid of it for this reason - it just didn't kill fast enough to finish them before they returned fire and alerted the entire settlement.
Now, if you want a silent sidearm that does the trick, look no further than the Manticore Tormentor. Note that even that will need the headshot damage mod if you want to kill an unshielded G5 dominator in one hit.
However, being able to dome a guard in a G5 dominator without alerting anyone is pretty potent for a sidearm. No idea if guards actually start routinely wearing maxed-out suits once your merc rank is high enough, I'm still only a rookie.
Sure, an Audio Masked Tormentor/Executioner would be great - it's the whole beggars and choosers thing though - even though no one (known) has unlocked the last engineer that has the modifications, I'd still be a long (long) way off unlocking them, hence why I was thinking that the beggar's option of G5ing the P-15 might be worthwhile. Added to by the fact the pistols actually do a decent amount of damage at G5. I've seen one CMDR dispatch guards with a G5 Zenith pistol that does just over 5 damage.
I can one shot scavengers with my G3 Executioner, it's the stealth aspect I require though since you can still raise alarms without Audio Masking.