Interesting. Good to hear you've put a lot of thought into this!

I'm curious... does the central panel of the 1000 come away from the rest of the front panel without cutting? If it does, that's great! Most arrangers have the entire top surface covered in buttons and sliders. It's major surgery to convert them to modules.

By the way, have you ever tried a Roland BK-7m module? Very small, surprisingly powerful...