Musical instrument snobbery is one of the weirdest things to me. I find it very hard to believe even budget gear is gonna hold back talented players or good compositions.
I think it is like a race car. Buying a fast car won’t make you a fast driver. A fast driver can perform miracles with a minivan. Pair a fast driver and a fast car?
Most of the professionals (the ones you buy music) are exclusive to a single brand. However, at the top tier of amateur competitions, the pianists have a choice of piano to use.
Sound is probably less critical than mechanism/feel. The professional concert pianists have traveling piano tuners who can tune the piano to their specific feel.
Broad strokes, and ABX’able
Steinway tends to have the most harmonics. It’s like a tube amp. New York and Hamburg factories have different sounds due to different supply chains. Many of the famous pianists of the 20th century used Steinway’s so it often sounds “right” or “familiar.”
Kawai is like the Harman of pianos. Driven by science. One of the first companies to switch to ABS keys instead of wood/ivory for consistency and one of the first to adopt robotics in manufacturing. Shigeru Kawai is like JBL Synthesis or Revel. The premium brand.
Yamaha has the lightest action, but is super fast. This doesn’t matter for classical music which is written in the era of slower mechanisms but can translate into a different instrument for modern jazz.
There are overtones. If you press an upper note lightly so that the dampers are lifted but the strings were not struck and then strike the bass notes heavily, the vibrations will transmit to the upper notes and vibrate the strings that are not actively played though actively un-dampened. This is like a mechanical intermodulation distortion.
Upright pianos do not have an escapement mechanism so your ability to repeat a note quickly is impaired since you have to fully reset the mechanism and lift off further before striking down again…
Earl Wild used to play on Baldwin pianos and then switched to Shigeru Kawai (in his late 80’s!). You can compare the sound between the Shigeru Kawai and a common Steinway.
Telarc’s A Window in Time took Rachmaninoff’s player recordings and reproduced them on Bosendorfer piano. Great comparison.