LSD is a lot more complex. I have experienced both, and I have never felt anything negative in terms of after effects of 25I NBOMe. Granted some are lucky in this regard and some are not.
LSD is great when you are self exploring, but eventually one does enough internal spelunking, and might enjoy a lighter affair of sorts, but still crave a lil psychadelia to go along with it. To me 25I offers an intrigueing euphoric boost everytime, while not on par with full out rolling on E, it bears some simmilarites mentally and physically for me, especially at lower doses. I was quite shocked at how the world shifts into HD vision so to speak. Visually at 1mg it can be quite a bit of fun, 1 mg to me is on par with 3 hits of LSD from the 1990's east coast varieties. It does lack 'head space' but as I mentioned earlier I no longer have the need to delve deep into my own mind.
For me 1mg is a well timed pseudo candy flip...... without the feeling of serotonin overload the following day.
All that being said based on what I know I would be weary to ever venture into the 2mg range, as .500 mg appears to be a good threshold dose, even somewhat surprising at times, and 1 mg is my initial dose sweet spot with sublingual ...... I am guessing .800 mg would be my sweetspot via nasal ROA. 2mg would be dangerous IMO based on what I know of my own mind and body....
As far as being brain fried? Like I said I wake up the following day feeling pretty damn good with really no ill effects, but I do not indulge in any other drugs currently so I am probably in the minority as far as a user of an RC like 25I. I also make it a point to load up on magnesium and potassium rich foods days before and after my 25I trips.