ghosthouse---Yup, the stiffness of cables coming from the back of components (especially lightweight ones) is a concern. A stiff power cord contacting a shelf can certainly "foul" the suspension, short-circuiting the isolation properties of any footer, not just a roller bearing. But those bearings, being so free to move, are the most susceptible. Careful cable dressing (delicious ;-) is in order.
One problem with softer bearing "bowls" is that the weight of a heavy component can actually cause the ball bearing to "dimple" the surface of the bowl, obviously not a good thing. If going DIY, I would give the steel drawer handles/pulls a try, in place of any plastic item.
