Well, I've had five nights now with my plain ol', unadorned, scientific Solo GonGs, and I am very pleased with their performance.
I have a 2014 Solo and was using it with a PNWT, and I have only the stock stems to compare these GonGs to.
So, I tried dry hitting through the GonGs, and comparing the ABV to the stock stem's, and I could not see any difference. I also tried just letting them roast for a full 12 minute session without any hits and the two bowls were, to my eyes, indistinguishable.
The slightly flared end makes for a slightly tighter "initial insertion experience" at first, but just angling it a bit gets you past that and then it slides right in like you've given it hours of foreplay. Generally, they fit the same as my stock stems.
I ended up with one at about 2.25", and the other two at about 2.75." Long and short? Short and medium? I dunno what you'd want to call it. I liked the extra stability of the shorter one, but I found I liked the longer GonG more simply because it was much easier to disengage the PNWT from it.
An extra half inch can make a real difference...
I preferred the airflow of the basket screen GonG as opposed to the stock stem.
I tried using the Solo inverted and at an angle, but found that, like my stock stems, the GonGs would slide away from the Solo sorta awkwardly. I much prefer keeping the Solo right side up.
I found that when using it with the PNWT, I prefer to go up to level 6, rather than my old "dry at 5" routine.
So I don't have any real criticism to offer here. I received exactly what I was hoping for, and my Solo sessions have become much more enjoyable now with the light filtration. The GonGs really accentuate and enhance the Solo's ability to be one heck of an effective medical device. And stoner tool.
Just another happy customer here...