The rotors in the Brembo brakes in the Grenadier are 316 mm in the front (12.4 inches), and 305 mm in the rear (12.0 inches). To my amateur eye, these are not very large rotors for a vehicle with a curb weight of nearly 6,000 pounds, a payload of around 1,600 pounds, and a towing capacity of around 7,500 pounds (all approximations). In addition, the Brembo brakes in the Grenadier are 2-piston caliper. Brembo makes other brakes with 4 and 6 piston calipers. More calipers allow for sequential clamping of the calipers, which is good on wet roads, and also allows for better modulation in the brake pedal, as well as greater clamping power. Multi-pistons will bring a vehicle to a stop faster - provided the tires have grip.
By comparison, after I lifted my Jeep JKU and went to a 35-inch tire, I also upgraded the brakes: 343 mm in the front (13.5 inches), 362 mm in the rear (14.25 inches), driven by 6-piston calipers. The curb weight of the Jeep was around 5,000 pounds, but it was running a 35-inch tire that needs more stopping power.
On paper, the brakes in the Gren do not seem to be "great", but owners are reportedly satisfied with them. I think
@Spjnr tows quite often with his Gren, and he has not reported any trouble stopping. Maybe he can add his experience here.