Quoting turbowop:
Compared to a 1g DSM.
I'm not sure why the difference. Both are negligible, IMO. But the GVR4 1st gear is weaker, so it's a poor choice if you plan to make power and launch the car.
Is the material weaker, or just more prone to break because of the taller gear ratio?
I agree, unless you are building a drag car, don't worry about it. I find with regular spirited street driving, 1st can be over pretty quickly. If you want to drag race, might want a 1st gen FWD gear. That thing is short.