It is possible that the popper that Bob Rohner developed is fundamentally different from the popper that J Rohner is selling.
They could be two different animals altogether.
Bob Rohner uses a high current low voltage spark. The gas mix he uses is matched to that type of spark.
Bob Rohner has shown at the end of his last video: at 14:50 of "Plasma Cycle is Not Air Driven".
https://www.youtube.com/watch?v=0fd-coQ84XU
This video segment shows that the gas mix is different between Bob’s system and that of John’s
In the rant about John’s accusation regarding Bob’s gas color in bob’s system, Bob explains that the color is different between his system and that of his brother John’s.
I suspect that Russ is using John’s gas mix which is matched to a high voltage low current spark.
Bob’s gas mix uses a higher percentage of helium than does John’s system and Bob’s gas mix is matched to a high current / low voltage spark.
Russ could have a mismatch between his spark(Low voltage/high current) and his gas mix(J Rohenr’s mix which needs high voltage and low current).
This gas mix/spark mismatch could be the reason for Russ’s relativly poor popper performance in his first test.
On another point, I suspect that John is providing in his popper kit a solid state Tesla like coil in this popper package to get a high voltage low current spark.
As an experiment, anyone who has a tesla coil lying around might try that spark source to see how that high voltage/ low current spark source matches up with John’s gas mix.
I like John's high voltage spark approach over Bob's because it is more elegant than the brute force spark that Bob is using.
And Russ has doubled down on Bob's current level with a truly huge ear ringing spark.
You bring up a very good point, but the color is also dependent upon current density and electric field.
See the paragraph about Discharge Color near the bottom of this page:
http://en.wikipedia.org/wiki/Noble_gas
The two brothers may argue that the other is doing something wrong because of the color of the discharge, but they are not doing the comparison using the same discharge conditions. So they will likely continue to disagree on this issue.
kcd