The Fantom G would be an excellent choice for me. Actually, it has all the features I've wanted all this time in a workstation; great sounds + great interface & full effects implementation (a VERY welcome addition). The G has a lot fewer arpeggios than the XS, so much is true, but bare in mind that editing arpeggios requires software in the XS (unless I'm gravely mistaken), and relying on preprogrammed arpeggios has never been my cup of tea anyway. Editing arpeggio patterns on the G should be awesome.
Another issue people complain about is the polyphony of 128 voices. Obviously a bummer for some (still, remember this is the same as the XS & M3). For me 128 voices is plenty.
AND, this is important; remember that the Fantoms have real, full-fledged samplers. This is not the issue with the XS (essential tools like loop crossfade are missing).
Also, the ARX adds polyphony (if I'm not mistaken). Plus it seems this technology would enable Roland to develop new synthesis engines to add to the system (again, not an option in the XS).
24 audio tracks are insane, and truly makes the G a complete, standalone unit. Disregarding the Oasys, the G seems to be the most competent workstation at the moment.
regards, Hugo