> So, is it possible to switch Local on/off for using polaris as a midi
> master keyboard

Marc,
I don't own a Polaris yet, although I want one soon, but the Polaris
Owner's manual says that the following switches control Local on/off:

Lower Function, Interface, 1 - Main Local control toggle on/off
Lower Function, Interface, 2 - Link Local control toggle on/off
Lower Function, Interface, 3 - Sequencer Local control toggle on/off
Lower Function, Interface, 4 - Main Chroma Interface Out toggle on/off
Lower Function, Interface, 5 - Link Chroma Interface Out toggle on/off
Lower Function, Interface, 6 - Sequencer Chroma Out toggle on/off
Lower Function, Interface, 7 - Main MIDI in toggle on/off
Lower Function, Interface, 8 - Link MIDI in toggle on/off
Lower Function, Interface, 9 - Sequencer MIDI in toggle on/off
Lower Function, Interface, 10 - Main MIDI out toggle on/off
Lower Function, Interface, 11 - Link MIDI out toggle on/off
Lower Function, Interface, 12 - Sequencer MIDI out toggle on/off

These should let you control how the Polaris behaves as a master
keyboard and how it responds to incoming MIDI messages, too.

Paul