FWIW, I did my own "chopstick" test with the RB-120 and found out that this mounting option was, in a word, useless. In a true parabolic, like the Briese or the Broncolor copies, the shape of the reflector is mathematically precise such that there is a focal point. With the strobe tube at the focal point, you get a nice large light source. Pushing the light behind the focal point gets you a very small hotspot (not too useful) and as you pull the light in front of the focal point, you get a ring-shaped light source that moves towards the outer rim of the reflector. This ring light acts gives a very nice even illumination of the subject without directional shadows and without a center hotspot, just like a beauty dish used close up. This effect is why people get these modifiers.
So, what I did for my test was set up the RB-120 with a boom stand on the center axis, with an unfolded 600ex-rt speedlite on the end. I had a Sto-fen diffusor on the speedlite so that it acts as a point source, much like a strobe head with a frosted dome. What I found is that I did not get the light patterns of a parabolic, and that the RB-120 has no focal point. It behaves more like an umbrella, pretty much filling the reflector no matter where I put the strobe. Needless to say, I was a little disappointed, but not surprised as I knew the RB-120 was not parabolic. It's a great modifier when used as intended, fantastic in fact, but I see no reason to indirectly mount the light in an adjustable way. The Dim sum reflector makes more sense to me for this product.