The drawback is what if you want to have 3 voices: a split voice (bass), main voice (piano or whatever) and dual voice (strings or whatever) - well you cannot ! The above scenario is very common as one needs to layer with a softer background voice especially for slow songs. I know that DGX has a combo piano and strings as ONE voice but you cannot choose it independently.

If YAMAHA corrects this deficiency, I think more players will buy it. However, most novices would not notice this until they play it in a few months and increased their playing skills and then it's too late to return the product. Also the registration memories is very limited compared to CASIO. It's very limiting to use the keyboard in live situation. As for CASIO, it's quite versatile BUT the voices are inferior in quality (not very noticeable to most novices).