Slightly off topic, I don't do opiates anymore, but I saw some real, uncut #4 dope the other day for slightly over 4x the street price in like 2014-15. It was real though. Real heroin is now a "luxury" drug.
IMHO fent dope fucking sucks. The only use that I could see for it is the low price being good to stave off withdraw for physical addiction. It has almost no euphoric or recreational properties to me. The last time I did a shot, it was most likely fentanyl, and all it did was make me angry, feel anxious, vomit multiple times, and go to sleep.
U-44700 was the only synthetic opiate analog that I even remotely enjoyed , but I OD'd twice off that stuff trying to chase a better high. It's like it was good, but not good enough.