Tidy,
If you need sampling - I am unfamiliar with the Tritons believe it or not - then you could still get the X6 as a partner for your Kurz.
If you are looking however for an additional 88 key instrument, I suppose you could get a G8. Lots of people here love the G and I understand that even the somewhat negative reviews of this workstation always mention that Live Mode is fantastic. You might want to ask G owners like MadaHorn and JimKnopf to give you their opinions on the G. They love it and own it and so their opinions would be based upon a much longer time with this instrument than I had. I auditioned for a grand total of nine hours in three different shops and was left "cold". But, JimKnopf feels that the G is light years ahead of the X.
Another option would be an X8. You are already familiar with the X engine.
There is of course the Korg M3. Again though, not my cup of tea. When I bought my X8 this past February I auditioned it against the X8. The M3 IS nice, but the X8 just felt and sounded MUCH better for MY needs. As for the OASYS? I think that the price is ridiculous, and money was no object for me. For 4,000 USD, I would have bought it in a heartbeat, but at 8 grand? Unless it makes orange juice for me and gets me a date with Shakira, forget it!
The PC3X gives you amazing synthesis possibilities that the G and the X cannot touch. That much is certain in terms of V.A.S.T. vs the Fantom's (powerful) S+S engine.
Kurzweil's plans are to focus continued development on this powerhouse. With the deep pockets of Hyundai backing them, the new Kurzweils could very well reclaim Kurzweil's position as the state of the art that they held with the unveiling of the K2000 back in the day. And believe me, nothing then could touch it terms of synthesis power and flexibility. Legendary artists like Pink Floyd, Pete Townshend, Paul McCartney, Paul Shaffer, Stevie Wonder, Herbie Hancock, and many more were and are Kurz users.
I remember a Keyboard article featuring Pete Townshend. When asked about his K2000, he said (paraphrase since Pete uses words we can't use here lol): "Get the K2000. It's all in there and you don't need any other f*****g musicians."
I wish could offer more positive comments on the Fantom G, but I am unqualified.
I am also glad that you got to hear the PC3X and see its specs. I would be very saddened if you just took my word for it. I am pleased that I steered you in the direction, and very pleased that you did the research
I noticed on your gear list that you too own a JP-8000! Isn't is a GREAT synth?? Yes, there are "better" VAs now - in fact your new Kurz has the built in VA-1 engine - but there is a character about the JP-8000 that makes it one of the coolest VAs I have ever played. I will NEVER part with mine. I hope that you never part with yours!!
Best,
Vlad
Note: I am not connected with Kurzweil Music Systems at all. I just know Kurzweil products and their great history. I bought my K2000 new when it was first released and still today it is a VERY important part of my rig, and an instrument capable of astounding possibilities.