It’s not clear Steve whether you are doing the studio work at home to replace using your producer and real musicians or if it’s just for personal consumption .

If you are just laying g down tracks for your producer to get a good idea of what you are aiming at in terms of your songs thst will then be played by session musicians , then the pa4x is really all you need as any serious mastering , mixing etc will be done by the producer , studio engineer etc .

If it’s just for home consumption and you have the desire and money then go for it with this caution :

If you are predominantly composing music for the country / Nashville type sounding industry , you will get virtually no benefit from the Kronos in terms of better sounds for that genre . The pa4x beats the Kronos on virtually all natural accoustic sounds except perhaps some of the pianos and electric pianos but in the mix you won’t hear that . The Kronos does not have guitar mode or the tricks and articulations to make natural instruments sounds realistic .

You would be spending money that would in fact give you minimal additional utility.

Obviously if you just want to experiment with very many sounds and are into sound creation and sculpting then the Kronos is your guy .

Just my opinion