Just noticed: has this long overdue bug/feature request been overlooked in this bug list ? (which can be boiled down to: MIDI Thru is missing in Reaper)
MIDI timing in Reaper
It was asked for by a number of people in that thread (among which EvilDragon), and it appeared today in the french forum.
So following the 2009 thread, here are some threads that mention the issue:
http://forum.cockos.com/showthread.p...76#post1405876
http://forum.cockos.com/showthread.php?t=144134
http://forum.cockos.com/showthread.php?p=1752003