+1 vote from me.
Every midi track to external gear need this.
Just a simple field like Cubase has where you enter your required delay.
Reaper just have to use that as if a plugin with that reported delay exist.
Sonar has for midi tracks where you enter in ticks.
But I'll bump the other thread linked to as well.
EDIT: OK that was locked for us mortals.
And here how ProTools also has really useful fields in mixer is maybe the best overview you could have.
You both get delay introduced on that track, total how much that track is delayed in project and a field to enter your own value.
Let's say late in the mix process you have to re-record something, or just add something - and want to know total roundtrip delay you get. You can deactivate plugin until track you are to record on gets minimum roundtrip delay.