My friend, the CT-X is a good keyboard but we cannot put it on the same level as, for example, an MZ-X or PX-560.
The CT-X has a very good sound engine combined with a good DSP system.
When you get tired of the CT-X sound, the PX-560 will still have resources for you to continue editing and creating new Sounds due to its great Synthesis capacity.
Hexalayer, ADSR, polyphony are some of the PX that gain in quality.
Not even the new PX have as many features as the PX-560 and PX-5S. The new ones are very good in terms of sound quality with the new sound engines.