I have a long Moduline workbench with drawers and a cabinet. Given a reasonable length and load, the shelves are strong and won't sag. Since you are hanging your cabinets, I don't think you would load them heavily anyway. They are well made and finished.
For floor tool cabinets, the steel ones (I have Proto) have a more satisfying heft and operate more smoothly, orbably because of the weight, among other factors.
Andy