+1 on a heavier duty roller box.
Luggage will work, but most aren't designed for the weight of plates, ammo, helmet, etc. If you find one that can handle it reliably, please let me know.
Regardless, it needs to roll. Carrying that stuff will injure you in short order if you have to move it any significant distance (go to the gym... yeah, yeah, yeah...). It carries different in a duffel on one side vs. on your person