I have both the VG and the GVG
I bought the VG at a local shop, while waiting for the GVG to be delivered (GVG must be ordered from vaporgenie.com).
I used the VG several times before the GVG showed up, and found it, after an initial newbie adjustment period, to be VERY effective for successful breathru's.
After using the GVG, the thing I found better about the VG, is that unlike the GVG, it doesn't have a small hole, under where the screen is. The small hole, on mine, restricts the amount of air that can be drawn through the GVG, which makes me have to inhale for a longer period of time to take the full dose.
The VG, on the other hand, has no narrowing of the airway thru the VG and allows for virtually unrestricted airflow as you inhale, This allows me to take the full dose within a second or two.....
I definitely believe the faster you can inhale the full dose, allowing for extra breath to continue to fill your lungs with air, makes a huge difference in the onset and intensity of my experience.
Maybe my GVG has an exceptionally small aperture that restricts the flow more than most, but would really love it if they would make a version, that had unrestricted airflow like the VG, in that regard (ie. a bigger hole in the glass, under where the screen goes in the GVG).
As cool as the GVG is, I don't see any major disadvantages by forgoing the glass. I don't need to see.........
Smoalk more..............
IMHO