Jlien X, what is your BounceBufSizeMsec set to in Preferences->Audio->Configuration File? This is more my curiosity so I understand your setup better.
I have been leaving mine at 250 lately, but admittedly not been doing MIDI much these days. When I tested the OP above I had someone sitting here watching as I did, and didn't drop any notes (I did 5 passes on a 4 bar loop twice). I am also curious how much the interface drivers play into this equation, since I have been looking out for dropped notes lately and am not seeing this.