Alex,
You are right on most, if not all of your points. Nevertheless, software is where the fastest (r)evolution is at. We saw this happen already in soft synths, soft samplers and now soft arrangers. Obviously software needs 'general purpose' computers, and that's usualy where the problems start. :-)
It is clear that both hardware and software based arranger setups have their merits, flaws and specific uses and we should not fall into any macho comparisons.
As for me I have always been more interested in what systems would NOT let me do. That's why I have given up on hardware samplers and arrangers. I agree that, in the case of arrangers, this is - for the moment - taking a step backwards. But as the french say: "Reculer pour mieux sauter". Keep up the good spirit.
PS: It might indeed be a good idea to start thinking on 'rearrange' the discussions into hard- and software forums.