Let me write my review.
The fireplace is impeccable. When it operates, the radiator thermostat on the other side of the house doesn't even turn on. The house has poor to moderate insulation, with an open basement below and an uninhabited upper floor. It heats up or at least maintains the temperature throughout the 140 square meter house according to the cold. In the area where it is located, it easily reaches 24-25 degrees, naturally decreasing as you move towards the back, but it still maintains over 20+ degrees. It saves on wood compared to the classic fireplace, of course.
Get it yesterday if you have a classic fireplace and want to upgrade it. It does the job.

I installed it on 10/21, the third winter, in the Athens area, in an existing open fireplace. The cassette fit perfectly without any issues, only a hole was made in the chimney bubble because I passed a 20mm stainless steel pipe inside the existing one. Its performance is very good, it raises the temperature by 4 degrees in about an hour in a living room-kitchen area of about 50 square meters. I permanently have the fan on level 4 because it makes quite a noise afterwards. In terms of consumption, I control it depending on the weather, around 3-4 kilograms of wood per hour. Overall, it is a very good cassette.

I searched and saw several fireplaces before I bought this one, and it was the one that won me over without having any particular knowledge in the field. After 1 year of use and 7 cubic meters of wood, I can say that it is an excellent purchase, especially since I have recommended it to others and they have the exact same opinion. A small disadvantage is the small combustion space, which is not a serious issue, because I only had one instance where the wood didn't fit, while usually I can place 2 or even 3 pieces of wood. Of course, we are talking about typical wood that is cut and sold in woodshops, not wood that someone may have cut themselves for an open fireplace. The other small disadvantage is that the vermiculite, which is only located in the upper part, can easily fall off after hitting it with wood. It may cause some anxiety the first time, but it can be easily repositioned and you will learn not to hit it forcefully when placing wood. The fan does make significant noise at high settings, but it has excellent airflow since it is a heavy-duty double fan with a central axis. From here on, the positives begin. Excellent construction in all aspects, with cast iron plates and a self-closing door for safety, which can be positioned to open from the side that suits you. The draft (in my installation-chimney, of course) is excellent and the fireplace lights up with ease. If the wood happens to be less "willing," I slightly open the ash drawer for 5-10 minutes and the flame becomes very strong, helping the wood to ignite immediately. Obviously, this is not a recommended practice, but it helps with damp wood. Once the first pieces ignite, all subsequent ones have no problem because the fireplace manages them perfectly with its air controls. The electronic air regulator for the fan is excellent, with 3 different options. 1) Manual adjustment to one of the ten (10!) air volume levels. 2) In this option, the fan speed is fixed at one of the ten levels, as desired by the user, and the fan simply turns on and off automatically if the fireplace is above or below a certain internal temperature, so there is no need for someone to manually light or extinguish it. 3) This option is the best, as the electronic controller increases or decreases the air volume according to the temperature of the fireplace chamber, without the user having to do anything. When the thermometer reads a temperature of 85-90 degrees, the fireplace is at its maximum efficiency. The control of the internal airflow towards the combustion chamber is excellent, better than any other fireplace I have seen. It has two discreet metal controls instead of one, like other fireplaces. Each one allows air to enter from different points of the combustion chamber for better control, while air also enters from multiple points in the upper back part, which greatly helps the combustion of gas residues in the secondary burn. The response of the flame to the controls is immediate (like a brake-gas pedal) and allows for absolute and immediate control of the fireplace's temperature and wood consumption. I measured the weight of the wood, related to the thermal capacity of this specific type, and found that it indeed corresponds to the 14KW of the fireplace with 80% efficiency in relation to the needs of the house for one day. I had estimated the needs of the house approximately (square footage, volume, insulation). So the fireplace seems to burn as stated nominally and as needed for the space, confirming the claims of the manufacturer's losses, at least with the approximate, perhaps slightly "makeshift" approach I followed.
Furthermore, it is connected to the house's piping network and has the ability to draw air from the outside for those who do not want to pull from the indoor air of the house towards the combustion space and the chimney.
I would recommend it again with confidence, but probably the VI90, as long as it fits in the hearth, to have a slightly more comfortable combustion space, although, as I said, it is not a substantial problem.

I have it for 3 years, I consume 3.50 tons of wood, and the house, which is 100 square meters, has 23 degrees. The choice was not for central heating, but from the moment I saw the performance, it has been the central heating for the past 3 years.