A little comparison of Tasers.
1DV is roughly equal to -3AP.
A Ruger Super Warhawk is 9P -6AP. That is the strongest handgun available out of core. Its damage is the same as a Colt M23 loaded the same.
A Defiance EX-Shocker is 9S(e) -5AP. You lose 1AP and gain the electrical traits. You also lose range with the taser, but gain the ability to use it in melee at slightly reduced damage (8 instead of 9).
Lowering defense is better than armor penetration because without a net hit you do nothing. Once you have that net hit they are equal if you are fine with either Physical or Stun damage as a result (AP is better for physical damage or for shooting through barriers).
The best damage code for a machine pistol is the Remington Suppressor at 7P -1AP. We could load it with APDS to get that to 7P -5AP. This is the same damage code as a Yamaha Pulsar, but without the electrical effects. You do lose some range with the taser, but you gain the electrical effects and legality in the bargain.
What some of these weapons net you is the ability to burst or full auto fire. Assuming that we can add a gas vent 3 and a collapsible stock to almost all of these we are looking at RC in the 5-6 range (More with higher STR or certain augmentations). This means we are looking at full bursts or simple action full auto with minimum to no loss from recoil. That's 4-5 dice our enemy loses and we can count at a rough 3 to 1DV. So that will net us an extra 1-2DV on average.
That means we can bump our suppressor up to 8-9P -5AP. That puts it on the level with a Defiance EX-Shocker for potential damage.
A Savalette Guardian does 8P -1AP. With APDS we are up to 8P -5AP. We can short burst ever round while resetting recoil compensation. That means we can take 2 dice from our enemies or 5 (but will start wracking up recoil, so this is an every other round option at best). On rounds we short burst we are looking at a rough 1 increase to DV. So the guardian almost equals the power of a Defiance EX-Shocker.
Burst and full auto fire are good options, but mechanically better for people with low pools (since the first net hit is the most important and the decrease to defense tests makes this more likely). The taser wins when it comes to damage and other effects when you can operate within its range and you are already likely to hit. In the end you can be effective with any of these options. Pistols gets you tasers, concealable options, and burst fire capability (no full auto). Automatics gets you the ability to get full auto and up into the bigger leagues with AR's, but excludes you from using the awesome, and legal, power of the taser.
Automatics covers a wider range of options for someone with only 1 skill for combat while pistols gives more varied options to a character who will have multiple combat skills and the augmentations to make them work.