Cool - this thread almost looks like bluelight again.
Obviously this substance (whatever it is) is virtually untested on humans, so whatever effects i'm describing here can say nothing about possible long term damage produced by this substance (or it's by-products). But in the interests of sharing knowledge...
After a few goes on the supposed 6-apb pellets, here's a few thoughts. I like this shit on it's own merits, but with a few caveats. The overall basic effects do (for me) have a lot in common with mdma/mda - more like mda to me, but still different enough to notice in a pepsi challenge.
On the downside, the side-effects, while similar seem much more prominent to me than on mdma/mda (but closer to mda): these manifest as teeth clenching, dry mouth, high temperature/sweating, eye wobbles. The side-effects for me from a single dose are akin to what might get on very high dose mdma (people tend to like these side-effects; i suppose through association with high dose mdma). I've had a headache at the end the first time i did it, but not subsequently - i guess the headache came from the teeth-clenching, cos i made an effort not to chew on later goes.
Another feature of this chem for me is the front-loaded effects: The best bit is the first 4-5 hours, then it tails off slowly to after-stimulation (although not unpleasant for me), making 8-12 hours in all. The timing of the different stages of the hit remind me of methylone more than anything: the best bit at the start, followed by lots of stimulation (though with the big difference that the nice bit was 2-3 times longer and nicer, and the stimulation never made me feel yuck like m1's stimulation - ymmv). I've found redosing too long after the first not always to be fully effective (it doesn't always recapture the initial euphoria). Although i have found redoses can make it a lot trippier. I also find a fair bit of stimulation stays with me into day two (after a bit of sleep), but also enough good mood juice to make it not feel wired (to me).
This stuff (whatever it is) is its own substance with it's own good and bad sides. But i (tentatively) think it has a place for me - i like the long effects; while chasing the initial euphoria with redoses may prove frustrating, accepting the profile for what it is, i still get a good long 8-12 hours work out of it (music - how i usually use mdx); not to mention a fair bit of work the morning after. This long effect profile isn't everyone's cup of tea though. Also, with the heavy side-effects, i don't think there'll be as much scope for upping doses (like there can be with mdma).
While i wouldn't choose it over mdma or mda (given half a chance...), i would choose it on it's own merits (given a cheap, pure substance) - and it pisses all over meph and m1 for me (which always felt much more unhealthy on the heart/BP, and never lasted long enough).
/by the way - suggestions it might contain amt sound sort of right on paper, but i would DEFINITELY have noticed an amt hit (this was a phen buzz, not a tryp buzz).