Vadim_C, if you have numbers or references to prove your point about Robert's tests being flawed or the results incorrect, please present them. You have heard the phrase, "put up or shut up", right? Otherwise, as far as I can tell, your arguments are based on assumptions, conjectures and/or speculations and have really taken this thread off course.
I do not believe I find myself trying to prove that a reflector can grossly changed the light measurement of two lights with the same light output.
Essentially what OP did he compared the guide numbers of the strobes in a nonstandard manner since the position of the lightmeter was not in the usual location. But that does not change the essence of the test.
You need references ? Good.
Here is one from all our favorite Paul Buff site:
We get a lot of questions asking, what is the "guide number" of your flash unit? This term is not wholly reliable because it relates more to the angle of the reflector than to the actual amount of light produced. For example, a flash unit with a given amount of light output will register a much higher guide number (f-stop at 10') if it has a narrow angle reflector (for telephoto lens) than if it has a wide angle reflector. But the actual amount of light is the same in both cases…it just covers more area with the wide angle reflector (at a lower guide number). In comparing flash units, the max GN of a flash unit is usually given for ISO 100 film. When it comes to choosing a flash unit, you have to be careful, as these measurements can be altered. It is common practice within the flash unit industry (for marketing reasons) to provide the max GN at the smallest coverage, as this will provide the longest focal length. Such a focused flash unit is more powerful, which produces a higher Guide Number, implying a more powerful output. Therefore, the max GNs of different flash units are usually not directly comparable. Studio flash units are designed to be used in many different configurations, with different accessories. The angle of coverage will be different in each case as will be the achieved guide number for a given amount of emitted light. As merely an indication of output, we publish the max guide numbers, noting that they are not true measurements of what you can do with our lights, as the real output will be determined by how you choose to modify the light.
The OP presneted the Elinchrom as two times more powerful than Visatec Solo. Sure it could affect the decision of a casual reader when considering Elinchrom versus some other lights.
I hope I presented my point in easy to understand manner. If not so be it I am not going to spend my on this.