A 2000 C1 Disklavier was purchased for $10.5k, suggesting $7.5k for a standard C1 is a strong deal if in good condition.

A G1 series piano was bought refurbished for $6.5k, highlighting the C series as a higher class and potentially better investment.

Kawai GX-2 offers richer sound and is noted to be $10k+ less expensive than a comparable Yamaha CX model.

Some owners perceive little improvement from a Yamaha U1 to a C1, indicating the upgrade might not justify the expense for all.

While some find the C1 lacking, others suggest it is an upgrade from the U1, particularly in sound and action.

Kawai’s Millennium 3 action is praised for its smoothness and reduced maintenance needs due to its construction.

A technician's inspection is crucial before purchase to assess the piano's internal condition, despite its appearance or perceived light use.

Carbon fiber actions in Kawai pianos are noted for durability and resistance to humidity compared to the traditional wooden action in Yamaha C1/C2.

Owners suggest using a piano cover at half stick to noticeably reduce the loudness of a C3 model in smaller rooms.

The C1 is considered a step up from Yamaha's G series but may not satisfy those accustomed to higher-end brands like Bösendorfer or Steinway.

The Yamaha C1X is often described as having a brighter tone compared to the mellow sound of the Kawai GX-1, with Boston GP156 having variable quality.

It’s noted that C3 through C7 models may be built with a slightly higher-end process than the C1, potentially affecting sound and build quality.

Grand pianos longer than 172cm, like the C2, are generally preferred for better sound quality over shorter models, regardless of brand.

The C3 features a longer chassis than the C1, resulting in longer strings and a slightly crisper bass sound, suitable for those seeking deeper tonal quality.