I own the Yamaha MotifXS and XF, I am interested in getting the cp4 because the weight is so much less, and in live shows I mostly use the piano sound.  My question is what type of wood was used, and has anybody had a problem with the wood swelling due to differences in humidity, resulting in keys sticking.  I live in RI and my only concern is that the untreated natural wood will act like an acoustic, but as a stage piano being moved frequently it will be harder for me to regulate.  I had contacted Yamaha and received a reply that I will quote below.  Just curious if anyone has had a problem with this at all.

“Hello Michael,

Thank you for contacting Yamaha support.

Though we don’t have much of a history with wooden keys failure to draw on, it is definitely a possibility to watch for.
Following are some notes concerning the CP4 and climate:

“During extreme changes in temperature or humidity, condensation may occur and water may collect on the surface of the
instrument. If water is left, the wooden parts may absorb the water and be damaged. Make sure to wipe any water off
immediately with a soft cloth.”

“warranty does not cover (a)
damage, deterioration or malfunction resulting from accident, negligence, misuse, abuse, improper installation or operation or failure to
follow instructions according to the Owner’s Manual for this product...deterioration due to perspiration, corrosive atmosphere or other external causes such as extremes in temperature or humidity;”

If you have any additional questions or problems, please feel free to contact us again.

I can’t give you any advice based on personal experience, but if you have reason to be concerned about moisture damage, I would recommend putting some packets of Silica Gel into the case with your piano.

This is the same type of desiccant manufacturers ship with products that are sensitive to condensation.