Yeah I read that, and it sounds very cool. But that is just the back wave.
But even if this technique 100% emulates the open-backed approach (which I am cynical about), the HD800 have perforated metal sheets making up the ear cup, so they are 'open-fronted' as well as open-backed. Having a sealed ear cup will definitely change the sound.
And then there is the pads. Anyone who has tried different pads on headphones will know how much they change the sound, and the pads are different.
A lot of people over-focus on drivers, and they are probably the most important factor in how a headphone sounds, but everything affects the sound.
What's behind the driver, what's in front of the driver, the materials the assembly is made of. It all has an effect.
Personally, while I find the HD800 mids to be lovely, and soundstaging to be out of this world, I never was a fan of the peaky treble or the lack of deep bass extension, so I'm not that bothered if they sound different. I might well prefer them.
Sennheiser is very unlikely to deviate much, if at all, from their HD800 series house sound.