but having looked up aMT's LD-50 (which is a lot higher)
Just remember the LD50 is for rats/mice, who have a much better metabolism than ours and so can stand a much higher dose per body weight than we can, and that the LD50 is when 50% of the rats/mice die, the lowest dose that has a good chance (say 10%) of killing someone is usually much lower, often as much as 10x lower.
To put it into perspective:
LD50 for MDMA in rodents: 100-300mg/kg which would be 6.5-19.5 grams in a 65kg adult if the dose translated to humans, it doesn't though, and human LD50 for MDMA is thought to be closer to 30mg/kg, so 1.95g in a 65kg adult - plus remember that's the dose when 50% of people will die, would you really be happy with a 20% risk of dying, or even a 5% for that matter? Because if not then the safe dose decreases dramatically, and that 1.95g for MDMA will become more like 400mg for an individual with no tolerance.
Now look at AMT:
LD50 for AMT in rodents: 20-30mg/kg.. That'd translate to closer to 3-4mg/kg in humans (so 195-260mg), and that's when 50% of individuals would be expected to die, nevermind just 10% or 5%.. 200mg is a dose that *should* put you in hospital and that's not something I have any doubt over. I think even 100mg of pure AMT is overkill and getting into riskier territory, and I've seen people manifesting with symptoms akin to serotonin syndrome from around 110mg before - along with the incident with 180mg that nearly killed one of my old school friends.
I can say without a doubt that getting away alive after taking 200mg of AMT freebase is something you should feel very lucky about.
To put it in perspective, at 40-50mg AMT is just as strong a serotonin releaser/reuptake inhibitor as something like MDMA, and at 150mg it's as strong an MAOI as Harmaline. Harmaline at a single dose has killed people just in combination with stuff like cheese and other tyramine containing foods, combined with a serotonin releaser or reuptake inhibitor of any kind will definitely hospitalise or kill someone. Taking 200mg AMT would be like taking just 1 and 1/3 doses of Harmaline along with 3-4 doses of MDMA, that's definitely something you'd need quite the miracle to survive.
You said you've taken similarly high doses in the past, people have taken 150mg of PMA too, or taken 5mg of 25I-NBOMe, and survived before. You've been extremely lucky that you survived this time, and that you didn't end up in hospital previous times, and I wouldn't push that luck again
Most people who take PMA will survive even if they experience serotonin syndrome, but that doesn't make PMA any safer to take, same goes for AMT at these doses - most people just means the majority, and doesn't rule out 5, 10, or even 25% of the people who take it dying.
I know there are some batches of AMT out there that are weaker and where 40-50mg isn't a solid trip like it is with the higher quality stuff around, but one should always assume they have normal strength AMT, or someone's going to get hurt.
Again like I said before I hope this doesn't come off as disrespectful at all, but your experience is absolutely what I'd expect in 50% of people taking 200mg. There is nothing unusual about being hospitalised from 200mg, and I really really hope no-one tries those kind of dosages any more, because it's not the first time I've heard of people exploring those kind of dosages.
I think the best move right now would be to send off a sample of the AMT to Wedinos for testing. I'd honestly be surprised if the results came back as anything but pure AMT though, since as I've said your reaction was what you should expect at that dosage - it's your past experiences where you've had no such reaction that I'd honestly be more questioning of, and it wouldn't surprise me if you received much less pure AMT in the past if you were able to push the dose range so high without any issues.
Regardless it makes sense to send it off for testing, because if something is up with the batch people should know whether or not that had anything to do with the reaction experienced - and if nothing is wrong with the batch then it'd be good to find that out so it can serve as further evidence to remind people that such doses *will* get people killed.
Hope you guys are doing well and have recovered fully since, I know it must be horribly traumatising having to go through that. I've been close to the edge before with a couple of drug experiences and it's probably the most terrifying thing one can experience.
the batch could be in question too but 200mg is a dose that can most definitely kill someone, I'm not at all surprised you experienced serotonin syndrome with that huge a dose. 
![:\](https://bluelight.org/xf/BL_Images/Orig_Emoji/wrygrin.gif "wry grin :\")
