Looking between a Harvia cilindro vs Spirit 6 kw

I have a cedar brook sauna that will be 4’W x 6’L x 7’ 6” Ht and am looking for the best bang for my buck situation when it comes to the heating unit while still being able to provide a good sauna experience. I am between the Harvia Spirit and the Cilindro 6kw. Both are comparably priced, so the main difference for me pertains to heat up times and general sauna experience. If there are any people out there with a good understanding or some experience with these sauna heaters, any in sight you might be able to provide would be greatly appreciated!