I've found what I think is a great way to control your light shows with a Korg-M50.
Start by setting up an individual Combi for every song you are likely to play at the upcoming gig.
The M-50 has four "Chord Trigger" buttons just above the keys - within easy reach while playing. You can program these buttons to play chords comprised of up to 8 notes. That seemed like a useful feature when I bought the M-50; but it turns out I only use the buttons on one song. But these buttons are perfect for sending midi triggers to your light controller.
You can individually set each button to send a specific note on any midi channel you choose. This means that for each song you can easily, while you are playing, trigger four different light Scenes or Shows. I've set it up so that the first button is the basic setting for the show, the second button is the chorus show, the third button is the first lead show and the second button is the second lead show. It works great.
There are only a couple of tricks you need to implement.
* Set your light controller up to operate on midi channels that your keyboard rig isn't using, e.g., my keyboard rig uses midi channels 1 thru 6; so my light controller is set up to accept signals on midi channels 7 - 12. Do not record any Scenes/Shows in a place that can be triggered by the midi channels you are using for the keyboard rig.
* Go into "PAGE SELECT/Timbre Param" and set the midi channel(s) that you are using for the lights to "EXT."
* After you have set the midi channels that the chord trigger buttons are going to broadcast on, go into "PAGE SELECT/ZONE DELAY" and set the lower and upper key range to G9. That way the keyboard keys won't send midi messages to your light controller.