In bought 3 grams a couple months ago. I would easily rail 200-300 mgs in a night.
My job requires that I be alert and very functional for my 7am start. I always felt like I could redose forever and had to force myself to stop. It was pretty easy to stop redosing, but even at 200-300mg a night, it was a very mild comedown. Insomnia was quite pronounced, but I am a light sleeper and many drugs induce insomnia for me. YMMV. Also felt quite caustic to snort. Orally worked well too, I guess I'm just a sucker for snorting things. Both ROAs made me feel tingly all over. Orally and insufflated felt like they had similar bioavailability.
After my 3G bag was gone, the only reason I never bought more was because it seemed too good to be true. I could see myself easily developing a cocaine style psychological dependence where I could just redose forever. I read lots of stories here on bluelight where I noticed this pattern of use developing with 3-fpm users.
It's a strong drug in its own way though. Paradoxically mild/benign, yet powerful and all encompassing. I bet if you push the envelope with this one some kind of dark side would rear its head eventually. Considering its RC status and its lack of history of human consumption, I chose to not pursue this one further, even though it was a lot of fun.
I read this entire thread a few times, and my gut feeling told me to lay off the 3-fpm.
Totally fun awesome drug though. I think I'll just save my money and brain for Coke and ketamine though when I feel like partying. I have enough issues with those two as it is. Stay safe bluelight!