Electronics in general do not like vibrations/shock of any kind. I cushion all my esc's for this reason. If I would stick the Viper esc to the metal chassis, I would use 1 or 2 layers of thermal conductive foam tape. You get the benefit of one giant heatsink that way and still reduce those micro vibrations.

I've done it with the Quark 80B and 125B. I've even done it with the Tekin RSpro with good results.