Well, my experiment this weekend got a bit derailed, unfortunately. None of my friends were using any substances (other than a tiny bit of weed briefly), and one of my friends was worried about anyone appearing impaired in front of his parents.
In advance for the weekend, I had prepared a capsule containing 100mg 5-mapb, 20mg 2fma, 2mg 5-meo-mipt, 3mg 4-aco-dmt, 3mg noopept, 3mg sunifiram.
The noopept and sunifiram are nonspecific potentiators, but I had some concerns about the safety of combining sunifiram with stimulants so kept the dosage very very low.
Anyways, because I didn't want to be too fucked up around (mostly) sober friends, I took 1/3 of the capsule at 10 pm, before going to a movie (guardians of the galaxy), another 1/4 or so later during the movie at around 12 midnight, and then finished the cap at 1:30am.
As such I never felt the full effects of the originally described dosage, but rather kept myself going at a mild buzz. All in all it was very pleasant--I was feeling chatty, subtle waves pleasure, pleasant tingling feeling all over my body (from the mipt I would guess), significant color enhancement, random emotional connection/empathizing with people, the movie, etc.
All in all it was a great experience, though of course mild because of the dosage schedule. We ended up sitting in my friends back patio with a fire going till 3:30am or so. It's 4:30 am now, and we're winding down for the night. I'm still feeling pretty stimulated. But the other effects are mostly gone. I took 1mg etizolam to calm me down/get me in a state where sleep is possible. Hopefully I won't have to take more.
Because of the staggered dosing, I can't really comment on the duration question I originally set out to answer. I would say the desirable effects lasted until 3-3:30. Actually the stimulation I'm feeling now is still pleasant--just in the speedy 2fma way only. Anyways, that would be 6.5hours from the first ~33mg dose at 10, but just 3 hours after the last dose. I imagine I will still be feeling stimulant effects in the morning when I wake up. Judging by 2fma's usual duration. I've heard a bad report or two about usig 2fa instead, but I think it would be much better to find a shorter acting stimulant to pair with the other here--2-fma is just too long-lasting.
EDIT: it's now 11:30 the next morning, and I can confirm I'm still feeling pretty stimulated. I fell asleep just fine, but who knows how restful that sleep was under the influence of the 2fma. I suppose I'll find out when the 2fma finally wears off.