I sometimes miss MDXX - though not the after-effects - and played around with mephedrone, methylone and butylone when they were still UK-legal, seeking an approximate substitute...but the moreishness and general dirty feeling of meph soon put me off, methylone wasn't as gentle as expected (and brought on 12-hour comedown of anxiety, restlessness and insomnia similar to a moderate dose of speed), while butylone was...well...nothing special. But reports on 6-APB, much as I enjoyed MDA the few times I had it, have convinced me not to try it: at least half of them are horror stories, and much as the OP's report's amusing, it does sound like an act of calculated self-harm from start to finish. Sure, it's your life, do what you want with it...but taking a massive dose of a dubious RC after a substantial hit of AMT? I understand the Fear and Loathing appeal of such a binge, and God knows I've been reckless to the point of addiction and amphetamine psychosis in the past, but, uh...look what happened to HST in the end. He burned out, destroyed his abilities as a writer, spent more than ten years repeating himself or churning out (for the most part) atrocious parodies of his earlier work as a sports columnist for ESPN, then blew his brains out with a Magnum. A figure, perhaps, more to be admired (for his early work and genuine don't-give-a-fuck exuberance) than emulated, unless neurotoxicity, brain damage, and fading into a pale shadow of yourself - however educated - don't bother you. In which case, it's hard not to wonder if there's an underlying death wish/or if you're just young/young-at-heart enough to still believe, deep down, that you're invulnerable and it can't happen to you.
As I say, I've been reckless and binged on everything from weed to rock and oxy (but I know I have a death wish), so I'm not criticising anyone...sure, choose your own hobbies, but there is some truth to what other posters have said: this kind of high-dose recklessness ('reckless' doesn't start with a 'w', by the way), is exactly what leads to hospital admissions, deaths and prohibitions. But if the OP reads this, did you ever get into that MXE? I tried it a couple of times, looking for a K-substitute when none was around, and it struck me as bearing the same relationship to K that meph does to MDXX: a vaguely related (experientially) substance, in the form of a developmentally challenged second cousin, shallow as a crepe and leading down much darker pathways. I took excessive doses both times, and hit the suicide-despair side of dissociative effects of a bad K-trip, with none of the transcendence, otherworldliness or pleasant anaesthesia of K. So I shudder to think where it might have taken you...(small doses, to me, were just annoying, vaguely suggestive of dissociation without really going anywhere).