I microdosed acid quite a bit. Too much actually at some point, and there are negative effect - anxiety, depersonalization, weird mood from Chtulu's realm and whatnot, ...
But overall it was amazing. People say they microdose to avoid the psychedelic effect but I beg to differ. The essence of psychedelia is perfectly encapsulated in microdosing. It is just felt sub perceptually. there is a malicious pleasure to take a substance that reveal the subconsciouss in such a way that it is felt mostly subconsciously.
For me, I could definitly feel "it", even as low as 5/8ug (it was very pure lsd though). It enhance focus for some activity, new outlook on life and social interaction, sharpest sense (especially vision)(goes hand by hand with->), you see new details everywhere, therefore more creative and "flow"-ish. Overall good mood and reconnection with nature. On a long period of time, I even began to have synesthesia - not all crazy bonkers like I high dosage but particular music would evoke very precise set of colors, so I could just listen to them beautiful tunes and emotionally rest in the colors. It also made me eat more and more fruit because they were so vibrant and colorful (especially tropical fruits). Big reconnection with the inner child and animistic stuff.
I think it's an incredible way to take psychedelics and it will play a great role in a psychedelic revival. That is, if not used primarely for all the performance outcome. I want to try again soon with mushrooms (for martial art and changa^^), acid is man made and tend to be more egocentrical of a molecule, more tiresome for the brain too - I really think that we should only take natural psychedelic substance. Even if there is some downside on precision, those areas of uncertainty are the core of it.