One thing worth mentioning - I have some freebase harmalas and experimented a bit to compare DMT trip using this mushroom trick with sublingual harmalas before DMT vape.
Harmalas: they slow down literally everything, including come-up and come-down. It's like you want to get to the fireworks show but everything gets slower including dressing up before leaving the house, driving to the place, the show itself and then the return home. Visual space is easier to navigate and a bit more vivid than with just pure DMT. Additionally the come-down is a bit too long for my taste and harmalas leave me with some headaches after the trip.
Post-mushroom microdose: the only thing that is slowed down and extended are the fireworks using the analogy above. In my experience the CEVs are far richer than with harmalas. Brighter, more colorful and even easier to navigate. Another thing that can happen are cool auditory hallucinations (you know, the ones you get on heroic mushroom dose in complete silence).
To me this
mushroom way is definitely an upgrade to harmalas. Maybe one day I will mix the harmalas+pre-microdose and will let you know.