the "perfect" arranger does not exist because no manufacturer wants that. they make their living from selling different products to different buyers. all-in-one arranger would be easy to make, just make it modular, both hardware and software wise. but none of the big players will play this game.
they could produce a basic, simple, but high quality hardware (keys, screens, buttons, mainboards, etc) and make several different "expasion cards" for everybody's needs, or extra OS options.
but this is NOT their interest. a new company may be doing it, to gain market share, or dramatic changes would determine the old competitors to take this way...
modules are the future. it's been the same with computers, and the same is going on right under our eyes lately with some of the arranger manufacturers, but of course, not the big 3.
i am confident in about 5-10 years, things are goind to be waaay different. some more flexible and clever approaches will happen, too bad that can not change the reality quite over the night!

i am looking forward to the moment when one of roland, korg, yamaha will introduce the open-system arrangers!

[This message has been edited by adimatis (edited 03-24-2008).]
Yamaha S770, Studio One 3, EMU 0404USB, ESI, ATH, Dell. And others.