Looks like more and more people are going to use Reaper to automate the pedalboards so I think it’s time to start a thread.
This topic has grown from another thread where I tried to make Reaper project switch presets on MC6 controller: Trouble with MC8 + Disaster Area midi box 4 - #3 by barneco
At the moment, I could setup a MIDI track in Reaper, which sends any PC and CC messages to MC6, so I can actually control anything setting up a MIDI track in Reaper. This lets me just add a MIDI track to our band’s live playback project, and it switches everything I need through all our 1-hour show. Cool!
But there is a problem which I cannot find the solution for: Reaper function called “Chase MIDI note-ons in MIDI playback”. It, well, chases all the MIDI messages which are prior to cursor in the track. So if I want to start not from the beginning, it immediately sends all MIDI messages from the earlier part of the track, and it makes MC6 crazy and even gets it frozen sometimes.
I found 3 places in Reaper menus where this chasing MIDI function can be disabled, but if a disable all or any of them, nothing changes. I guess there is another menu where this chasing MIDI function could be disabled globally, but I could not find it ever since. I google a lot, started a thread on Cockos forum and even emailed to support, no answer so far.
The good news is probably I am not alone in this search? At least @barneco uses Reaper to control his monstrous board too 
Any ideas to solve the problem appreciated.
Also if you have any questions about MIDI automation in Reaper, feel free to ask. I am not considering myself as an expert, but have some experience