Anyone that is sequencing in an arranger (or even WS) these days is missing 95% of the capabilities and ease of use of a computer based system. I think that all arranger sequencers really NEED is fairly basic abilities, but a strong emphasis on what is needed at the PLAYBACK end of things... easy editing of sounds used per track, basic track global offsets for volume, effects, dynamics, etc., and then easy ways to manipulate the playback of the file... Markers, conditional loops, preset mute and solo groups, integration with the style and multipad section, things like that.

The arranger is still primarily a 'performing' instrument, and would benefit from those areas being the focus of development rather than trying to simply ape (poorly) the capabilities of computer sequencers. Sure, you need basic 'scratchpad' recording, for when inspiration strikes when you are away from the house, but little else, in truth. Let's face it, most us us have a computer with MORE than enough horsepower for a good sequencer... And the added real estate on a decent monitor makes editing operations that are a PITA on a tiny arranger screen so easy to do, one is tempted to do it more often.

I haven't used an on board sequencer for anything more than a scratchpad since the early nineties (maybe earlier!) and don't miss the hell that working on detail editing on a tiny, tiny display puts you through...