The Fantom X is suppose to hit the shelves in 'limited' numbers sometime in April AJ. I would be very surprised if Yamaha announced any replacement for the Motif ES before 2005. You should get a pretty good resale on your Motif ES if it's in good condition. It's still under warranty plus you have plug-in boards also.
Yamaha has the motifator.com site where a lot of questions can be answered. The only problem is the answers they provide are usually not in a step by step process but from my experience they always seem to omit some part of the procedure which is like giving you electricity but not the switch to turn it on.

I never did get the whole procedure on how to Save an Auto Load file on start up even though I repeatedly asked them for a step by step explanation. (The Manual was useless as it did not explain it thoroughly). Plus Bad_Mister must think he really is BAAADDD if you know what I mean.

One question I asked him he came back and arrogantly lambasted me for questioning some of Yamaha's procedure on hardware implementation. I wasn't berating him either; just asking a simple question and an explanation as to why Yamaha did it the way they did. After he lambasted me I turned around and scolded him for his attitude and demeaning manner saying to him that the motifator.com site was suppose to be a 'support' site not a put down site where they treat their customers like trash. After that incident he never replied to any of my questions.
Needless to say my Motif ES7 was returned shortly thereafter. Mike Martin and the other two guys were always helpful though.
I guess if they view you as a 'threat' or controversial or whatever they basically shut you out (not out of the site but nip you in the bud by not replying to your questions. At least that was my experience anyway. Maybe that is Yamaha's protocol not necessarily the support staff's protocol. But then again maybe it IS the support staff's protocol, ie., "shut you out by not replying to you if they view you as a threat or whatever."

eBay may be your best bet for getting the price you want for your Motif ES AJ. Although I don't buy and sell on eBay because of some of the security risks and all the fraud that goes on there, some people don't seem to mind all of that and have had good results.
PS: Make sure you demo the Roland X or Triton Extreme firsthand before plunking down your money. And spend inordinate amounts of time doing it. That way you will be better prepared to really know what the Fantom X or Triton Extreme has to offer. And don't be in a hurry. They will always get more in stock if the store only has one or two at the time. Plus they will ALWAYS have the floor model to demo.

Best regards,
Mike