I just downloaded the Jo-Gunn catalog and to me it reads more like a comic book than a technical brochure. In over 40 year I have never seen a company so aggressively mislead their customers before. Their publications have your reading one blatent lie after the next as if no one would know. They even fabricated a new antenna specification called "Audio gain" so they could pile on more BS and promptly gave themselves 30db of this new gain. I'm not even going to ask how one measures this. Just know when a antenna manufacturer starts talking about improving your audio, start thinking the BS is just about up to your nose and run.
Then we have a 36 foot boom with a whopping 125 times power multiplication!!! Compared to what? The boom is like 5 feet short of reaching this gain over an isotropic radiator never mind gain over a dipole. How about the "V" series that claims to be circular polarization? It's not even remotely possible to form CP with all of your elements inline, in the same plane. They claim their Son of a Gunn 3/4 wave ground plane is the best. Model that jewel in EZNEC and you'll see it's the best at talking upwards with little energy on the horizon. The simple vertical dipole will out talk it every time (except to airplanes, space ships and Martian's).
For years I have heard repeated JoGunn's BS, but I never paid it no mind, just like I am not persuaded by anybodies advertising.
I never trusted their hype. That is why some years ago I bought an I-10K just to see what all the high gain hype was all about. More recently I did the same with the Gain Master, and a few others. I saw differences, but they were never like I heard suggested by others.
Shockwave, I don't think it comes as a surprise to you, but all advertising pushes the envelope in the puffing category.
A while back I modeled the basic design (absent the true dimensions) for the Son of a Gunn, and I find what you suggest, albeit is not quite as bad as you describe...as only radiating to the birds.
I wouldn't buy any JoGunn antenna however, just for the reasons you note. Mainly because they do not divulge any real information about their products, even to their own customers...excepting as you note just more BS.
I have modeled my sketchy ideas for several of their designs and after comparing what I find to some of their competitions models, I find them always lacking in some small ways...and for sure they are not equal to the hype they spew to the public.
After all this time of comparing antenna responses at my location, I still am convinced that my Starduster antenna is just about as good as any that I've ever had up. Even after more than a year comparing it to my Gain Master, I find very little difference in the scheme of things, and my Starduster is lower at the tip by about 6 feet.
There is nothing special about JoGunn antennas.
...runna pile-up on 6m SSB