Mass isn't the issue. It's the
Moment of Inertia (resistance to spin, which is a function of mass and radius) that could be the issue.
Per my rough calculations, the moment of inertia of an AM performance wheel and 1714's Lexan wheel differ by about 25%, and the actual ratio is slightly lower than this as the AM wheel has extra material near the axle that I didn't account for. I assumed an AM wheel is a rim and 3 sticks that span the inner diameter and the lexan wheel was a solid piece of Lexan.
Since you guys have the robot, have you noticed any adverse effects on performance? I'm still of the opinion that these wheels are super slick.