So much of the reason for arrangers getting the thumbs down from session pros is the deliberate dumbing down of the feature set, IMO.

Roland use a Fantom engine, Korg use a Triton, Yamaha... not sure if the engine is Motif based, but many of the samples sure are. But where they diverge is the depth of control. Zone ranges... Most workstations make no rules to follow. Any Part can play any range of keys, or velocity range, or a combination of both. Arrangers.. Fixed assignments to Upper, Lower, MBS, sometimes a third split. But nowhere NEAR the flexibility of their WS cousins.

You can't blame the engine. It's well capable of any of this. It's the software, the assumption that, if we get enough choice, it will confuse us. As if getting into the depths of TVNs and Style editing isn't complex enough already...! These arbitrary choices you are forced to make on arrangers, effects routing, zone ranges, tone editing, even patch storage and recall, etc., etc., are most likely the reason many pros eschew arrangers.

Shame, really, as very little needs to be added in the way of OS improvements to compete with workstations. But, of course, therein lies the problem. If arranger capabilities WERE grafted onto full WS OSs, that would be the end of the WS as we know it. And profits stay high when we are forced to buy TWO different products to do two jobs, rather than making one capable of both. Money, pure and simple.

Mind you, the last couple of sessions I've been on, I've taken my G70 in to do piano parts, rather than use the Kurzweil K2500X in the studio. That piano is so warm and intimate, on the right material, it is giving even the Steinway a run on a few tracks (we have a 1928 baby Steinway). And on live call gigs (no idea what we will play) I'll take the G70 over my K2500 simply because it is easier to call up sounds and effects for splits and layers in a hurry. If I have a lot of time to prepare for a show, then probably the K2500 gets the edge. But for fast and simple meat and potatoes, the G70 can't be beat.

But I sure wish it had MORE flexibility, and editing depth, and I might be able to let the K2500 go... Nah! I still need a great sampler and some whacked out sounds from time to time (two of it's strengths)...