[BBray_T1296]

Generally speaking, motor controllers don't experience much force, if decently protected.
Also, the wires (generally larger gauge), will assist in the retaining of the controller, as long as your crimps are properly done (or soldiered [as in wire to crimp, not ever crimp to MC, before I get hounded])

This year our electronics are fairly out in the open because there is literally nowhere else to put them. In our 1st match of Dallas a ball landed squarely on our right side electronics board, ripping out the (poorly crimped and not soldiered) right side drive motors and even SNAPPING A FAN IN HALF.

In the past we used plastic hardware to screw the MCs down to some corrugated plastic, which you can poke mounting holes into with just a precision screwdriver, so our mc mounting is hardly robust, yet we have never had a problem.

Zip-ties are nice for those on the "no velcro and no hot glue on the motorcontrollers" bandwagon, because they are 100% removable and allow for easy swapping of MCs if it becomes necessary.