I played some levels (mostly with Blue Suns in it like Zaeed's Loyalty) again with different builds and SMG loadouts. Level 30 Infiltrator, 4/5 SR Upgrades, Visor, N7 Shoulders, Capacitor Plate, Stabilization Gauntlets, Stimulator Conduits and the following skills and SMG loadout:
Heavy Disruptor / Squad Cryo / LvL1 Incinerate / Tempest SMG using Cryo / Widow using Disruptor
Heavy Disruptor / Squad Cryo / LvL1 Incinerate / Shuriken SMG using Cryo / Widow using Disruptor
Squad Disruptor / LvL1 Cryo / Incineration Blast / Tempest SMG using Disruptor / Widow using Disruptor
Squad Disruptor / LvL1 Cryo / Incineration Blast / Shuriken SMG using Disruptor / Widow using Disruptor
Squad Disruptor / LvL1 Cryo / Incineration Blast / Tempest SMG using Cryo / Widow using Disruptor
Squad Disruptor / LvL1 Cryo / Incineration Blast / Shuriken SMG using Cryo / Widow using Disruptor
Some of my observations (obviously all are subjective and also my playstyle plays a role):
- I clear the levels faster with Squad Cryo, maybe because frozen enemies take more damage
- It's less risky for me with Squad Cryo because
a) I can instantly see which enemies are currently not participating in the battle and thus either focus on them for the damage boost or ignore them because I know I'm safe from harm for sure for a short while. I can't always tell if an enemy weapon is currently overheating though in the heat of battle and also they sometimes like to change positions then if they are not hiding behind cover. Both scenarios are usually less desirable than a frozen enemy.

my squadmates don't "steal" too many enemy shields which I like to destroy with my Area Drain. With Squad Disruptor I had quite a few situations in which I really needed a Drain and there were no enemies with shields around but a lot without shields that were still shooting. So Area Drain usually strips a lot of shields and let's me play without taking too much cover and then leaves enemies vulnerable to the Cryo Ammo fire from 3 guns.
- Enemies with overheating weapons tend to hide behind cover more often. That can be annoying. On the other hand some frozen enemies are falling to the ground. That can be annoying as well if you were trying to kill that particular enemy but it can also be nice because they need to get up first after the effect wears off.
- I wasn't able to 1S1K (without Cloak) those Turian Blue Suns Troopers with full shields and health when I used Squad Disruptor on the Widow. They had a tiny amount of health left. It was hardly a scratch of health but nevertheless... they weren't dead. Maybe they'd be dead if I used the Kestrel Torso with additional +weapon damage but I already use that on quite a few other chars and don't like the look of it too much.
- The Shuriken seems to have a higher chance of freezing enemies than the Tempest. I really noticed when I was the only one using LvL1 Cryo. While using Squad Disruptor + LvL1 Cryo on the Tempest I didn't have good runs, with the Shuriken on the other hand they went better. But I like the Tempest, especially the sound and the clip size although
the Shuriken isn't that bad either and has higher damage per shot. Don't know if that factors in when determining if an enemy freezes or not.
- The shorter freeze duration of a LvL1 Cryo is obviously noticable but it's still not that bad. When we were all using Squad Disruptor it didn't go as smoothly in comparison.
My ideal build would look like this: 1 Disruptor Ammo / 10 Squad Cryo Ammo / 10 Assassination Cloak / 10 Incineration Blast / 0 AI Hacking / 10 Assassin / 10 Area Drain
Unfortunately this is not possible because you need at least LvL2 Disruptor to unlock Cryo and I really hate the devlopers for this. Of course I can just add 2 more points but I don't like it. So in the end I'll probably just stick with
this again: 10 Heavy Disruptor Ammo / 10 Squad Cryo Ammo / 10 Assassination Cloak / 1 Incinerate / 0 AI Hacking / 10 Assassin / 10 Area Drain
I'd really like to have a fully maxed Incineration Blast instead of Heavy Disruptor because I rarely need the Heavy Disruptor. It can come in handy though at times to still 1S1K some enemies with stronger shields that I won't soften up with the SMG or the Energy Drain first but those situations are rare and I'd benefit from a LvL10 Incineration Blast much more. I don't agree with some people who say Heavy Disruptor is useless though. I agree however that you should always take Squad Disruptor over Heavy if you don't use Squad Cryo (or any other Squad Ammo for that matter). But if you are using Squad Cryo there's really no need for Squad Disruptor. Even the Geth levels like Haestrom are easier with 2 Area Overloads + Area Drain and Squad Cryo than with Squad Disruptor as far as my experience goes.