I'm not sure how easy it is to compare arranger mode and either Karma or MotifXS-like operation.

I may not be that familiar with Karma (played it a few times, but don't own it), but from messing with it, and from messing with the XS, I get a completely different interactive experience with those systems...

The biggest difference I came across, and one that is fundamental to arranger usage, is the concept of variations, fills, Intros and endings. Especially the fills.... On neither of the WS's (or any other WS, to my knowledge) do you get an instant drop-in IN TIME, for use as a fill. Everything is cued up in advance, or triggers immediately, but out of sync.

Now, I don't know about you, but the ability to kick a fill in at ANY time I feel like it is one of the fundamental plusses of an arranger system. Not to mention dedicated fills for most of the possible transitions (not enough for me, but certainly enough to avoid repetition, except for the Korg two-fill system [and break/fill ]). Then, of course, there are the dedicated intros and endings, with up to four of each.

This contrasts completely with things like the M3, XS, Karma, etc., which have a great selection of loops, but a far more contemporary mindset when it comes to control. Modern loop-based musics don't follow the traditional form concepts, and so you rarely find any of their ROM loops to have any kind of traditional structure, and their control system would not allow you to use them like that even if they WERE programmed that way.

For musics that started in loop production - techno, house, trance, D&B, hiphop, rap, etc., etc., they work perfectly (after all, it's what much of it was made on in the first place!), but for the majority of us here that work in more traditional musics, whether jazz, blues, latin, ballroom, country, rock, you name it... Well, they just don't offer the type of control paradigm that firstly, we are used to, and secondly, what works with the music.

How many of you have ever run an arranger where the fills need triggering a bar in advance? Not many, lately, I'd say. Yes, you CAN do it on a Korg this way, but I would be willing to bet virtually no-one DOES

So, I'd be careful in saying that arranger-like things can be done on a WS like M3 or XS or FantomG. Yes, you can get them to follow your basic chords, but forget inversions most of the time, and definitely forget dropping fills in at any time you want, and forget the conventional '4 intros, 4 endings, 4 variations and up to seven fills' that all of us are SO familiar with.

It's a shame, really, as I think that even WS's with Karma and chord following loops could benefit enormously from this control paradigm, if added to the control system it already has...