Well, that was interesting. First, run out of Sonic Rifle clips, then ignore somewhat sound advise to research TSL and research Sonic Pistol instead.
Ok, I understand your conundrum as you didn't have any high-damage weapons anymore. But you could have just went with Gauss Rifles + Sonic Pulser setup and it would have been fine 'cause you ignored those Lobstermen anyway (it was a good idea to do that btw as you were kinda painted into a corner). Personally, I wouldn't have equipped nearly my whole squad with the Sonic Rifles - one or two would have got a Sonic Rifle and the rest would have got a Gauss Rifle or Gas Cannon. Ammo management is a big issue early on when you can't do enough missions to make up for the usage, or said differently, you use more clips than you recover per mission for a net loss.
As for the Sonic Pistol, well, I never use them because the aliens phase them out quite quickly in favor of the rifles and cannons. Which means you'll eventually run out of clips and weapons to use and you'll have to manufacture ammo. Kinda defeats the purpose of switching in the first place (except maybe as an interim stop-gap measure). You have to realize that the clip sizes of the sonic weapons are all rather low. Sure, 26 sonic cannon clips sound like a lot, but that's only 13 clips worth of rounds the sonic pistol has. Let's just do a back-of-the-matchbook calculation between the three weapons on snap shots:
Sonic Pistol: 20 rds/clip * 80 damage/rd = 1600 damage/clip * 0.65 accuracy = 1040 damage/clip
Sonic Rifle: 15 rds/clip * 95 damage/rd = 1425 damage/clip * 0.75 accuracy = 1069 damage/clip
Sonic Cannon: 10 rds/clip * 130 damage/rd = 1300 damage/clip * 0.8 accuracy = 1040 damage/clip
As you can see, the damage/clip drops down steadily as you go from pistol to cannon due to fewer rounds, However, the Sonic Cannon makes up ground due to it's accuracy. Same for the rifle, though it's accuracy is a huge improvement over the pistol which leads to overall more damage. Of course, this calculation assumes the damage/rd is modified by the accuracy (which it isn't). Instead, accuracy measures how many rounds hit/clip. Taking this into consideration, all the weapons end up being around 1040 damage/clip.
The aliens never really phase out the sonic rifle and cannon, though eventually the cannon predominates by a large margin. So the cannon would be a better choice for a larger number of aquanauts except it basically cripples their movement if they shoot. It comes into more use once your team has the ability to MC aliens as you can shoot at them with impunity.
So is it a good choice to switch research from TSL to the pistol? As a stop-gap, maybe. The TSL isn't a be all to end all
weapon anyway. But, I highly suggest managing your ammo/grenades wisely especially if you are cherry-picking which sites you'll visit. And you may want to increase your manufacturing capabilities so that you can produce enough gauss rifle clips to supply your squad and/or manufacture things for profit.
IMHO, research can wait.
The standard sonar and wide array sonar do
stack with each other, so don't get rid of either until you get the Transmission Resolver which trumps both.
Just don't go adding more standard or wide array sonar modules as they will not provide any benefit than what you have currently.
The death due to friendly fire was unfortunate as the guy you shot had a primed Sonic Pulser. However, you had soldiers in a position to run over and grab the pulser before it went off effectively saving an extra sonic rifle clip or two (plus the kit). Instead you run away. All you need is 8TU to grab something off the ground and put it into your hand!