I thought I'd add my 2c to this thread as I recently had my first go at this chem.
its probably worth noting I did a low-moderate dose of mdai the weekend before and had no hangover or other noteworthy side effects from it at all.
my 6apb is fairly white powder which does not dissolve in water. that was my roa, I did a 1-5mg test first then dropped 70mg after an hour.
not a huge amount but I'm not a big guy either so...hit me pretty hard and was fantastic as long as it lasted. I kept very hydrated throughout and temperature was not a problem. I did not mix any other substance.
comes the time to go to bed and difficulty urinating was very annoying. I was still pretty stimulated even though I dropped at 17 and went to bed at 2AM, insomnia hit hard as I didn't sleep for one minute... it then developed in a headache/hangover.
It was present throughout the entire next day and got very strong by the end of it, I had to take some ibuprofen which did work..but I could sort of feel the headache still lingering once its effect worn out. I could sleep again at that point and everything sort of felt back to normal at the end of next day.
Sense of weakness on muscles for a few days but didn't particularly last for longer or bother me. a certain afterglow was left after, I wouldn't say my mood was particularly worse off the days after, I guess that depends on your baseline, in my case it felt pretty much the same if not slightly better, not easy to judge. my mood doesn't naturally swing much.
anyhow that bad hangover was definitely the worse side effect and fairly worrying. definitely was not dehydration.