It may be that both MPC's and arrangers are facing the same issue. A generation (or two!) have come along since they were musically relevant and have found alternatives that are as effective and FAR cheaper in software, while anything that adds increased functionality to the old hardware comes at a formidable price!
Yamaha seem to be the ONLY arranger maker that is continuing development of anything other than uber-expensive TOTL $4000+ arrangers or toy <$500 arrangers. Been over 8 YEARS since the PA1000. By contrast, the SX920 is only a couple of years old.
This pretty much mimics the way home organs bowed out. Eventually all that was left were the uber-expensive models. You can still buy reasonably priced B3 clones, but anything that resembles a more Japanese/European style organ is five figures (or more!). I think Lowery were the last 'affordable' home organ maker. It's looking like Yamaha are going to be 'last man standing' for affordable arrangers.
In the meantime, software that emulates MPC workflow is all over the place. But software arrangers are pretty rare and mostly labors of love, not polished professional offerings. Most of this may come from the fact that arrangers were generally FAR more content rather than feature driven. An arranger without a soundset or styles is the exact OPPOSITE of what the vast majority of arranger players want!
While computer software does an incredible job of emulating older synths, one thing that lags terribly is emulation of ROMplers (which were the sound engines of arrangers pretty much from the start). The most recent ROMpler emulation is Korg's Triton, and that's about it. So using that as the sound engine for a software arranger gives you basically an at best 1999 era arranger!
MPC beat making was all about sampling vinyl. The included content didn't make or break the deal...
Sadly, the only people that CAN make a decent software arranger seem to be those either exiting the industry, or are the last man standing and unwilling to cut into their current sales...
This is the PERFECT time for Roland (who only make toy arrangers any more) to come up with a software (preferably tablet) arranger and leverage their mature software AND ROMpler soundsets and great styles that aren't making them a penny at this time. 🎹😎
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An arranger is just a tool. What matters is what you build with it..!