Okay, I have positive experiences to report. I took my last dose of fentanyl ~10 days ago (after tapering down). I did okay last week on gabapentin and the gabapentin high masks the mild I was feeling. Then I read about loperamide and about 4 days ago, I took 60mg and nothing happened (and this is with gabapentin also, which gives me diarrhea) and then I took 120mg and voila, in 2 hours, I felt a nice body high that I hadn't felt with the fentanyl in a long time (since I was tapering down). It was quite good---you know, the feeling of taking a new opiate and experiencing the high for the first time, I felt it! Of course, I couldn't wait and so the next day I did it again and it felt great still. I've now been up about 50 hours (doing science) and I've taken doses of 120mg, 130mg, and 150mg of loperamide in that period, and the last one is just kicking in. I'm thoroughly enjoying this.
I should stop before it gets too far since I had tapered off the fentanyl. When I stopped the gabapentin (due to tolerance), I felt mild WD which needless to say has gone away with loperamide. If I wait 24 hours, the mild WD comes back so now I am getting into a habit of buying a bottle of loperamide pills per day which is crazy! It helps with my pain too BTW. I do have mild chronic pain still and I even just had a spasm pushing my back and the loperamide helps (or it could be the ibuprofen, but it's hard to say). If my pain is musculoskeletal, can loperamide work?
I don't think mixing gabapentin and loperamide works well (which is odd since it seems to potentiate the fentanyl) but by itself, loperamide is very effective not only for WD but also for the warm body euphoria that opiates give and a slight mental euphoria. I actually feel highly functional mentally on it so in some ways it's even better than fentanyl (I'd not be able to stay awake for 50 hours if I had extracted the fentanyl patch and was using it intranasally).
I'd argue loperamide is actually more potent than codeine or tramadol. I mean 400mg of tramadol wouldn't make me feel like this. 400mg of codeine would kind of, but I've only taken 150mg of loperamide. This subjectively is equal to me about 300mcg of fentanyl or 30mg of oxycodone.