about the question of neuro enhancement: i used some of this stuff like ritalin and cocaine at university occasionally when i worked as teaching assistant. and i've also tried in poker sessions. i doubt that it makes you a better poker player. maybe you can extend your sessions a bit or add a few more tables, but it wont increase your ROI i guess.
i mainly did it to compensate my biggest leak: weed
but since i got a bit more serious about poker i play exclusively sober. that's still the best option imo.