I remember the Buzz/Phooey discussion at TrumpetMaster. It went nowhere fast.
The lips open and close like a valve at a rate related to the length of the trumpet. Each fingering has multiple notes based on the wavelength being played. The pedal note is one wavelength in the instrument. Low C is 2 wavelengths, G is 3 wavelengths, third space C is 4 wavelengths. This continues until our lips are no longer able to open and close - due to pressure, tension or lack of being supple.
I consider the buzz or alternate start of lip vibration to be an insignificant semantic argument with no redeeming value. We are talking about the same thing: ignition of the lips, initialization of the vibrating mode. Regardless if one calls it Phooey or a buzz, fact is, we blow air through the lips with a certain amount of lip tension and they resonate. This blow can be a relaxed exhale to a forceful expulsion of air. Articulation comes later when we modify the start to "speak". To speak a "phoo or foo" we would need our lower teeth on the upper lip prior to ignition. That certainly does not line up with most embouchures - especially considering that most have an overbite (upper teeth in front of lower teeth). Perhaps for players with an underbite (upper teeth behind the lower teeth) phoo would be what at least they "think" that they are doing. Considering that ignition needs freely vibrating lips, beyond the exhale, it really does not matter.
Some players have trouble with a free buzz. That is in most cases insignificant as we always play trumpet through a mouthpiece. Some players have trouble with a buzz through a mouthpiece. This is also in many cases insignificant as we rely on the resonances of the horn to modulate and stabilize pitch. Some like buzzing free, on the mouthpiece or with some resonance enhancing scheme (leadpipe or P.E.T.E). Good for them. It never helped my playing and I never taught it. I certainly would not criticize another teacher with good experience in buzzing however-as long as the player is getting a well balanced routine every day.
I found the arguments at TrumpetMaster regarding this to be little more than annoying as the real issues of getting the sound started are masked in senseless arguing.
If we can't get our semantics to line up, then beating a dead horse is not productive. Let us just talk about ignition instead.
As far as Yamahas claim to deeper cups being more mellow, science backs this up. The more cup volume, the more it acts like a low pass acoustical filter - reducing upper harmonics (compared to a cup with less volume). Less harmonics is a "darker/more mellow" sound.
The throat/backbore indeed also has great effect on sound and intonation as well as efficiency. That has nothing to do with Yamahas claims at the mentioned website.
We should never forget that the target audience determines the semantics. The casual reader really could care less and at least gets some valid pre-chewed recommendations. As they advance in perception and capability, they go elsewhere for mor detailed info.