I wish Roland had have updated the BK7-m before they quit making arrangers!
If they had added the Chord Sequencer and the SN and VK sounds to the BK7-m, I would be in heaven! It's an amazingly good unit, in a tiny form factor. And they included the FC-7 input, which is pretty much mandatory in a module.
The problem I've found with large form factor modules like the Korg and Ketron units is getting them in close enough to your master keyboard to be able to easily, accurately and quickly get to any button you need. Korg only has a five switch multipedal, which IMO is not enough to get you hands free through a song, and especially if you are using one of these with an accordion or a guitar, hands free is your only option!
My first Roland arranger was an RA90... Compared to that, the BK7-m is a tour de force! I still take mine out with my keytar to jam and it never ceases to amaze.
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An arranger is just a tool. What matters is what you build with it..!