Hi Lenny,
I'm not a fan of Yamaha boards so I'm not really going to comment on those, especially since I've never owned one.
My suggestion to you is to think about what it is you want to do with the synth and what kind of music you want to do with it. That should help lead you on the way to getting the right synth.
The Triton is a great sounding synth. However, all of the sample-playback synths are limited to a certain extent. The Triton at least can be expanded and can act like a sampler. I agree with Inray that it's synthesizer is limited. However, that doesn't mean it is not capable of powerful sounds. It *does* however support sysex. The Korg sequencers do not support sysex and that is probably where Inray is confused. The Triton support sysex dumps to and from an external sequencer.
One route you may want to take is to go with one of the analog-modelling synths like an Access Virus and then go with a Roland JV-1010 for some of your bread and butter sounds. They are quite inexpensive. If you want a sampler (which is great for drum sounds), you can maybe pick up a used Akai S2000 or something similar. This route may be slightly more expensive than a single Triton but probably not by much. You may be able to get these units used too which helps cut down the cost as well as gives you some good sounding gear.
Unless you want to use the MPC2000 for a sequencer too (you already have Cubase though), the MPC is not the best sampler around. It is strictly for drums. You cannot map, for example, piano samples across 88 keys. You can assign samples (up to a maximum of 3) to its pads (16 x 4 or 64 separate notes).
The only thing that I will add here is, it is not a matter of what you own but the music you make. True, with lousy sounds, you won't go too far but simply owning the latest, greatest and most expensive kit won't give you that #1 hit.
HTH
Fernando