The cheapest turbine they have is 4300 euros. This is ridiculously high price. In Finland, you get a 2.1m diameter rotor for less than 1000 euros (controller, mast, turbine), and a full kits with batteries, inverter and solar panels for 1400-2500 euros. A 3.2m diameter turbine here costs around 4000 euros and 8m diameter turbine around 20k-30k depending on configuration. These are list consumer prices including taxes. The prices quoted in the Dutch "test" seem to around 4 times what you pay here!
The quoted average wind of 3.8m/s seems inland wind speed. It is quite obvious that there is no point in installing turbines in locations where the average wind speed is low, but they seem to get some power from the larger turbines, though the price level they have kills the payback times.
They correctly point out that taller mast makes a difference, but one point for large industrial turbines is ignored - industrial turbines do need a grid to deliver the energy. For small turbines, the idea is to use the energy where it is produced, avoiding cost of grid. Grid cost in Finland is around half of the the bill, and taxes around 30%. We have grid/transmission cost separately priced so you can select to buy renewable-only energy from grid).
They did figure out, which I assume most people in industry already know, that the diameter is the interesting factor. The power generated is in relative to diameter and square of wind speed and efficiency factor. There are lots of snake oil companies out there claiming bogus production numbers, which is unfortunate as it spoils the reputation of good idea. There can be easily spotted by calculating a wind area covered by the turbine and dividing that by price. As getting efficiency up by few percent tends to be very expensive, it is easier to just make simple blades few percent longer. The cheapest wind turbines sold here have continuous profile blades, and they still perform nicely, even though the center part of the turbine probably does not do much work.
We have 2.7m diameter unit (www.tuulivoimala.com, 500W nominal) at our vacation home we use in summertime. This is very non-optimal location, only northern winds and too much shadow for solar, so we took more diameter and big battery pack to offset non-windy periods. We use the power for lights, computers, 3g WLAN access point for network. Total cost of all electrical installation including lights, wiring, 2kW inverter, 980Ah battery pack, was less than getting grid to the place. Not enough for heating, but we burn wood for that, the plot is large enough to provide us practically unlimited supply of firewood. The power has been plentiful for our use. Electric chainsaw works for chopping the firewood, though we need to avoid continuously sawing more than 1 hour to avoid emptying the battery pack more than third :)
If you do not have a grid connection, the install cost of it will offset quite a big turbine and solar installation, so small turbines are very popular in vacation homes. And for vacation home, the more remote the better. Which means very expensive or impossible grid connectivity.
In Scandinavia, solar does not work early spring or late fall, so wind turbine here may be the only option if you need electricity off-summer times. Combining solar and small wind turbine makes a lot of sense as the electrical installation is similar.
The same thing applies to developing countries. It often makes more sense to go directly to renewables than build grid to every small village. In south solar power or hybrid solar-wind is probably more dominant.
They claim that turbine does not even make up the energy used in making it. This is true only if the turbine is located in a low-wind location, or it is faulty design (no diameter!). I agree fully that it does not make sense to install turbines in city areas where buildings mess up wind flows. The location has to be one with good wind conditions.
To our experience, if you already have grid connection, you do need more than just price of electricity as motivation for renewable energy installation, as the payback times are long (less than 10 years only in optimal locations). However, you get additional benefits, independence from grid, good feel factor of using renewables, not paying tax for electricity, etc. And the price of wind and sun is not going up.