Well, I finally did my experiment. I took a big dose of harmine + thh and tried smoking. I took enough harmine to get significant effects by itself. However, it didn't seem to affect the smoked trip at all. Maybe there was a longer come down, but the peak itself didn't seem any different, I don't think. Hard to say.... I'm not even "myself" when I'm in there, and comprehensive language to describe the experience is always difficult anyway, so ..... I don't know. It is possible that I required less vapor to get an effect. I'm not sure of that either. However, I am pretty sure that the trip did not last longer than no harmalas. That's what I was hoping for. I was hoping for a peak that would last like 20 minutes or something, but no, it was just as quick as always. I thought the maoi would keep the dmt acting in the brain longer, but I guess not.
The after effects did seem a bit different. The after effects kind of felt like ayahuasca, with a body load and I went through some heavy vertigo and disorientation for just a few minutes, but not nearly as long as ayahuasca. In conclusion, I probably won't bother with harmalas if I am smoking because they don't seem to affect the trip much.