Thanks for the replies, guys.
Traps are much-much more useful with Trap Expert. It's a lot more than QoL, like how it seems. Simply placing traps almost immedaitely allows you to set them up a LOT closer to enemies with stealth. Quick Tinkering is perhaps the best CC in-combat ability. Interloper + Hit and Run is a must, Sprint is not needed. Ambush is fundamental too.
In general, I don't see the reason to get feats for two separate weapons that both meant to be used as main source of damage. When an enemy is within AR range (or even a tile close), you can just as well kill them with a sniper rifle. Due to this, taking feats of anything else is a waste. Especially if they involve you wasting stat points too. Also you have to carry more bullets, often different caliber. A pistol can be the only exception as it won't fight the rifle, it supports it with boosting your Initiative and allows you to perform Kneecap Shot with the longest range and the cheapest AP. Excellent CC ability for any incoming melee.
In addition, with high Detection and Stealth, crawlers pose zero danger and are just sitting ducks. Even without Motion-Tracking Goggles with NV, you can easily spot them before they notice you and just pop them. They also cannot open doors. Paranoia helps your bad Initiative and is pretty much the anti-crawler feat for so many reasons. Once you are able to make crawler poisoned Bear Traps and see just how immensely OP those are, you feel like you want to farm these critters. Incendiary Traps are also amazing to trigger Fear and Ambush on demand where you want it.
Any case, here's a tried and tested DOM-proof Sniper build for reference:
https://stygiansoftware.com/forums/index.php?topic=10837.0
I get how strong traps are, I tend to use them only when I'm struggling. I did in the early game, now I rarely do. I still carry a few traps around for thought times.
During a previous test build a got interloper. Made stealth a lot more easy to use.
I guessed I could have done without, but it's definetly useful.
My previous test builds were to determine which side arm to use with a sniper. I tried pistols and Smgs. I decided to save pistols for a full pistol run.
I was undecided between AR and Smgs untill the last moment. Smgs a probably a better complement to Sniper Rifles, yeah.
Although I don't think I completely wasted that point really. Isn't 6 strength needed to carry that last unique SR?
About crawlers. I'm running a high perception build, and I carry around a pair of detection goggles. Still, it takes a few moments to spot them, and sometimes they still take me by suprise. They are less of a threat now, but I did struggle a lot with some early encounters.
I dread what pain in the ass they could be for a low perception build, especially since I'd like to try a psi build next.
All in all, in retrospective, I think I've ditched too many QoL talents, probably because as a newb I expected some crazy difficult ahead.
Thanks for your advice.