YAMAHA UX-3

[sam11791]

I saw a Yamaha UX-3 piano, serial #4448804. It's priced as $5500. It sounds almost same as a Yamaha U-3 which is about $1000 cheaper. Is Ux-3 a better build piano than U-3?. It has a x brace on the back of the piano. Does the x-brace make any difference? I was told the ux-3 is about 17 year old. Is this kind of piano ok to buy for a child who is a serious learner?