I really like adding the warmer on your automation control so that you don’t waste money by leaving it run unnecessarily. I looked at several online and the hardwired ones all had junctions. I would think there has to be some kind of junction box for the electrician to connect the rack warmer to the power? I suggest hiding that smart relays like the Enerwave or Remotec in there. Still have the manual on-off wired to the input of the relay for local control. Anything hardwired even to a junction box has got to look cleaner than seeing a plug in an outlet, yes?
If you decide to go the way of a GFCI breaker at the panel make sure to get the personal protection version tripping at 5ma and not the equipment protection which trips at 100ma. Also verify the current local building codes allow for using the GFCI breaker in lieu of the outlet.