I have experimented with this chemical extensively. A couple months ago I had an idiosyncratic response involving sub-lingual administration. I noticed what appeared to be an extended duration trailing off over several days. I had never noticed this previously. I discontinued use.
Recently I decided to consume this chemical and document my reaction. The trip report can be found here:
http://www.bluelight.org/vb/threads/718880-25B-NBOMe-400ug-An-Unintended-Physical-Reaction l. I repeated this a few days later with about the same dose and the same thing happened again. A short period of intense visuals followed by several days of confusion, tendency towards panic attacks, and blurred vision. Upon closer inspection I noticed the fog I was experiencing in my vision was intensely psychedelic when I would focus. When I stopped focussing and would continue my daily activities this would subside to an amorphous undulating fog of blurred vision.
This chemical has a high lipopholicity (logP ~3.84) which makes me wonder if what I am experiencing is a bi-phasic half life. A short distribution phase (probably into lipids) I interpret as a psychedelic trip. This might be followed by a much longer phase of slow elimination I perceive as less intense psychedelic visual fog, this phase appears representative of the terminal elimination half-life. This could explain why people using 25x-NBOMe more than once every few weeks require greater doses and why the tolerance last longer than other psychedelics. I am uncertain in regards to why I didn't notice this second longer phase the first dozen times I consumed this chemical. I guess I was incapable of recognizing the subtle details and overlooked this. This is only a theory.
I have found some benefits from this chemical. Their might be therapeutic effects in regards to it, probably requiring lower than psychedelic doses. The few positives I have experienced are outweighed by the negatives. I haven't had access to LSD in over half a decade and will probably never have access again. My previous experience with LSD and evidence from others show LSD is much more enjoyable, safer, and has many of the same benefits. I was once hopeful and optimistic the NBOMe series would be a safe, valuable, and enjoyable substitute for the therapeutic effects I once received from LSD. I did experience some minor therapeutic effects, these were overwhelmed by the negative effects. My youthful faith and optimism was misplaced. America is a country in crisis and it's irrational and inhumane drug policies are a manifestation of the magnitude of its social problems. Uncle Sam would much rather people have a chemical that causes death, psychosis, and almost guaranteed failure when used therapeutically rather than LSD. I learned an important and identity crushing lesson about the nature of the country l live in.
I don't plan to use this chemical again and recommend others don't use this chemical either.
If you have hopes in regards to the beauty of LSD or its potential they are justified. If you believe the NBOMe chemicals currently available are a substitute your optimism is naive. In the name of social stability in a time of crisis a human life is insignificant relative to an ant in America. The drug laws of this country are representative of this.