I've had both heaters on order since I placed my original order, that was always my plan when I signed up nearly 2 years ago. My tastes change from time to time so the cost of a spare heater is well worth it for my piece of mind. To compare it to my Mi2 and Mi2 they're very different heaters and for periods of time I'll prefer one or the other. Really what's the cost of a different coil to totally change the device. That's how I justify it .