I can see how you came to your conclusions eric65, because David has indeed stated many times that the PH tubes have tamed his 009's brightness (compared to stock JJs and also SEDs).
But the reason is because the PHs are considerably more transparent than the JJs. They simply let the music shine through more, whereas the JJs slightly corrupt the music by smearing the images and adding a layer of grain to the upper mids and treble, which is more fatiguing - there isn't necessarily any more treble to the JJs, it's just more obvious because it isn't as refined.
It's the fundamental nature of the improvement that means that David can be delighted that the PHs have smoothed his 009s, whilst at the same time I can be equally delighted that the PHs have livened up my 007s. If it was just a tonal colouration, one of us would have to be disappointed.
I should add that all these differences are probably objectively tiny. No tube change will suddenly turn Diana Krall into Ella Fitzgerald. So people may not even notice there's a problem until they come across something better. But I'm highly sensitive to grainy/etchy/sheeny upper mids and lower treble, and tiny differences in this area can matter a lot to me.