Funny I came to say something similar, the Fusion does multiple types of modeling, has the Alesis Ion (basically) synth engine + FM + physical modelling + Rompler + sampler , etc. You could throw anything you wanted on that 80 gig hd , convert SF2 programs, long samples , etc.Actually if it's an all in one synth you want, the Alesis Fusion is better in many ways, and stupidly cheap. Much easier UI to get into the FM and sampling on that, I thought. Great VA. And the 8 audio inputs are a cool idea... The weighted keyboard is good, but not as good as the Kronos
Of course the RAM was limited, FX were just ok, the keyboard maybe not up with the best of them but h**l you can get them for probably 500 bucks now and if you were willing to learn it, you could do some great stuff.
But yeah its buggy, will crash sometimes or not load certain programs (damn you, Mellotron Flute!), sequencer was shitty, not a good MIDI brain....I bought it to be sort of a "all-in-one" and within a month I was looking at stuff like RS7k or EMU Command Station to sequence on instead....I still like it, it's been one of my longest-in-the-studio pieces.