I have a WM8740 based desktop DAC (FireStone CustomCute) that sounds and measured as good as the three ES9023 (ODAC, iFi iDAC and UD100) I have. Implementation is the key. In fact, it is more important than what chips a DAC used IMO.
As James pointed out, the hardware spec on ES9023 isn't better than WM8740, so there is no inherent benefit to change from WM8740 to ES9023. Instead of focusing what chip is used, it is better to look for way to optimize the current design - and no, I don't think the WM8740 in X3 is at its best sounding (compared to what I have heard on CustomCute). But then again, it is in a portable player so naturally it is not going to be as good sounding as when it is implemented inside a desktop system. There is something to consider - even though ES9023 sounds good as a desktop DAC, it doesn't mean it will sound just as good in a portable device when everything is designed in very tight topology. Even among all the desktop DAC that use WM8740, there are those that sound okay and those that are great. The only plus I see on ESS chip is that they tend to be more highly integrated, so they demand less attention on the circuit around it.
WM8741 is pretty much the DSD enable WM8740 with additional digital filter for the most part. The hardware improvement from WM8741 to WM8740 isn't nearly as significant as the price jump (regularly 3~4x more expensive) has suggested. In fact, some higher end manufacturer still stick to WM8740 because they think WM8741 is most a marketing push to phase out the older chip so they can justify selling the newer chip on much higher price. Plus WM8741 sucks up too much power and not suitable for mobile device (> 4x the current draw compared to WM8740). In fact a dual WM8740 configuration is probably cheaper than one WM8741 and still draw less power. In any case, the hardware spec on both chips is well beyond what human hearing can detect. So again, it really is down to the implementation to make sure they can sound as good as possible. The chip itself is less important.