An excellent review that covers all the bases. The quality of reviews here varies from shoddy to excellent. This is one of the latter.
The upscale AWD: that's actually a coupler and two clutches - the inline coupler at the transmission to drive the rear diff by the propeller shaft can be toggled on or off. If OFF the vehicle is Front Wheel Drive. If ON torque is stolen to drive the propeller shaft and rear differential but the FWD is never touched. Then the twin clutch rear axle, (trade name GKN Twinster a British design also manufactured in China by them) has one clutch on each rear axle. By squeezing each clutch appropriately, what torque that is available is apportioned left to right as sensors/electronics decide.
One thing's for sure, if anyone claims 100% of the torque can be sent to the rear axle they haven't the faintest whiff of mechanical understanding, because the FWD is never touched! It is always on, just like in the Subaru, Mazda, Volvo, VW and all the other vehicles without a center differential. The Twinster AWD is like a cheap copy of Acura's original SH-AWD, but without the oversped outer wheels. It also lacks the facility to do what Audi and BMW offer in their $1500 rear diffs in the S4 etc., namely overspeeding the outer rear wheel in a corner. All it can do is apportion torque left to right, but a Torsen differential can do the same within limits, and no electronics to go wrong.
However, the Cadillac/Buick/Twinster AWD baffles the unwary journalist and subsequent reader. not to mention the marketing types whose only area of expertise is in selecting glossy photos and writing indecipherable aspirational text for brochures. I would rate the Blazer's upper option AWD as better than the mediocre average but scarcely leading edge. The discontinued Chrysler 200 V6 of 2015 had a similar system made by someone else, not quite as well thought through which took too long to automatically engage - four tenths of a second. Here, if the customer had already pushed the AWD button next to the shifter, the system only has to engage the two clutches controlling each rear driveshaft. It's the exact same hardware as in the Focus RS, but Ford was too cheap to install the ON/OFF coupler, which led to the clutches in the Twinster rear axle often overheating.
Beyond all that, I have to side with Unifor. In Mexico, where are you going to find a market for a $40 to $50K crossover? You could in China, where wages are higher and 300,000,000 people are essentially middle class. GM and the other car companies assemble in Mexico purely to save money and for no other reason. And GM is unashamed to do so, despite having 15% of the Canadian market and being about to close Oshawa assembly. They gave the same middle finger to even more US assembly workers. Today, Feb 4, GM started to dismiss white collar workers as well, with a 4,000 person dumping. Good luck finding another job if you're 50 plus and those higher-paid ones are the ones they dump. You're now a member of the gig economy, as our grand and glorious Finance Minister Morneau, who never missed a square meal in his life, blandly told the young a year ago. The barking right who still have jobs like to belittle those struggling to make ends meet on minimum wage - get a real job they say while hopping on their deluxe snowmobiles and scarfing down reheated frozen chicken wings for dinner. Corporate dumping by GM and others may hit these dorks and give them a new frame of reference.
Meanwhile, why bother to encourage GM or anyone else to import stuff they could have made here by purchasing their Mexican vehicles? If we all had decent-paying jobs as in pre-1988 non-free-trade days, we could afford a bit more to buy things made by our fellow citizens who had real jobs. Instead we are encouraged to look down on our fellow citizens down on their luck. Cheeses me off, especially when populist gorfs like Fraud divisively run Ontario into the ground spouting complete nonsense. We all categorize and hate each other's imagined type and politics, and meanwhile the money flows to the top where it's least needed. By design of the upper crust rich, I would surmise, who basically run the politicians. I was a white collar corporate type for decades, seen it all, and eventually came to abhor the scene. Nice people go to work at a company every day where they turn into unthinking corporate rah rah savages on a rampage to cut costs and screw the customer, then go home and become normal again in the evening. Something has gone seriously wrong, and GM typifies it.