Do you think heating miners are worth pursuing in countries or climates that don't really get that cold.

yes, especially for heating water. Even in hot climates you need hot water: Shower, Dishes, Clothes, etc.
Obviously it will not that much heat than if you try to heat a house in a cold climate, but thats where open source is so important: being able to build a system that is made for the specific usecase.

Also in hotter climates you usually have a lot more sun and therefore also solar panels and with that free energy, which can be used again to heat water or just heat the air which will usually give you more money back than selling the energy back to the grid