The taste for piano sounds is as diverse as taste for good wine.
One person may love a sound and hate another and the other will be the opposite.
I have shopped for a piano and a portable one for a while now and I believe that if you really want a nice piano sound, then consider a Kawai ES110 for the under $1200 price point, and portability is your concern. The CG700 has far more sounds, rhythms and other bells and whistles, but I agree that the piano sounds are not the same elegance as other dedicated digital pianos.
Because I wanted the sound to be better, I did also buy a console Piano CN35 which to my ear is very pleasing and often I prefer playing it compared to my 35 year old Yamaha C3 Grand.
My recommendation is to spend the time playing the instrument in the showroom, and using YOUR OWN headphones too. At the end of the day if the sound really bothers you, flog it on eBay or Craigslist and get the keyboard you really like . Life is too short to have to put up with annoyances like this .