To be honest, squeak, a full featured sequencer on board seems kind of overkill nowadays. I wouldn't want to do anything serious on the arranger itself, MUCH preferring to work on the computer. No itsy bitsy little screen is as good as a nice sized monitor, and there is usually only a fraction of the power of editing with on-boards. I like to work in a full featured piano roll environment, and have yet to see a decent implementation (or at least anything that stacks up against Cubase) in a keyboard.

A simple 'record the arranger, store as an SMF' ought to be enough, and then transfer to the computer for detailed editing. I like the Makeup Tools kind of editor on board, but just for fine tuning or changing patches, drum sounds, velocity and volume etc., on a global scale, but editing MIDI on some display smaller than a Commodore 64 seems so retro..... and bad for your eyesight!

I still think an awful lot of people are gaga over 'features' in an arranger that are done FAR easier in a laptop or computer - sequencers, HD recording, sampling.... And all at the cost of purely ARRANGER features like more variations, fills, flexible hold features, sequencer/style play interaction, break/fill/mutes, chord sequencers (groan!), things that are actually about arrangers.

My worry is that, as more and more workstation 'features' get grafted on, the arranger itself becomes more of an afterthought. That will be a sad day....
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An arranger is just a tool. What matters is what you build with it..!