I love the PA4X. Operating system has improved a lot, even over the Pa3X. You can now play styles from USB via a system called disk direct.
I've been able to find every style I need. There are tons of them out there, in addition to the ones on board and that Korg lets you download for free. Plus the 4x has a built-in midi-to-style converter that works well, if the original midi file was done right to start with.
All sounds, particularly guitars, pianos and drums are way better on the 4x than on any predecessors.
As far as out of the box, they make it easy to adjust the sound to your preference by the MAXX automatic settings.
If you use vocal mic, same thing is true, let the T.C. Helicon processor automatically analyze your voice and set the e.q., compressor, de-essor, etc., for you. Just check Automatic and adjust the input level and it does the rest. Of course you CAN set everything yourself if you wish.
There WILL be a learning curve as far as the operating system, but after that, I find it much better than Yamaha's.