I've not had a problem with the stock switch but think for the price another stock switch would be “plug and play”.
Not to but for those new here this is what we did when assembling the tractor. Like BCMike I thought the wire going to the intake heater circuit was too small and thought it should go through a relay (solenoid).The solenoid and wire came off a junk Honda, the circuit breaker and connectors were in my tool box. No major mods to the wiring, just ran a #12 wire from the starter to circuit breaker and clipped the #16 going to the preheater and used it to energize the solenoid.The tractor came with glow plugs and a buss bar but weren't being used, we added them to the circuit.