I've only made it through page 10 of this thread so far and I'm sure there will be some redundant aspects to my post, but I figured I should add my experience to the thread now that I have caught a good buzz from this stuff. A friend and I have tried a few things with it now. We both have a little tolerance, but not a lot. I think her habit is usually 40mg of hydrocodone a day, and mine is equivalent to 30 or 40mg of oxycodone a day. The first thing we did was snort 5 mg. There was a mild effect, and no immediate burning, but it quickly became evident that this stuff is caustic to the mucosa. Nonetheless, I was curious what vaporizing it would be like, so I threw a few mg into an "oil burner". It definitely melts and seems to vaporize properly, and the pleasant effects come on nicely, but we could feel the causticity in the lungs as well. There is a mild but unmistakable pain immediately upon inhalation that definitely deterred me from continuing. Next, I made a 15mg capsule for my friend to take the next day. She reported that this was not enough to give her a buzz, but allowed her to comfortably skip a norco dose, so she estimated the strength of 15mg oral to be like 10mg of hydrocodone.
Then, a couple nights later, we iv'd some, and that was where this stuff really shines, in my limited experience so far. I have read a couple reports of people saying it burned at the injection site, but with the low doses we required, that was not the case at all. I dissolved it at the concentration of 10mg/mL. It dissolved fine after a few minutes of stirring. I went first to test the waters and shot about 6mg, which turned out to be a very nice dose for me with this roa. I would concur that the comparison to hydromorphone is pretty apt. That 6mg felt I guess like maybe 1.5-2mg of hydromorphone; nice rush, very clear headspace and pleasant clean buzz. I only stayed up for like an hour and a half, so I can't say how fast it wears off or what the comedown is like compared to other things, but I was still feeling nice when I went to sleep.
Based on the causticity and short duration that other people have reported, I would say this stuff might be a pretty bad choice as a staple for maintaining an opioid habit, with the possible exception of oral administration (assuming it won't fuck with the stomach lining or something). Even though eating it is clearly inefficient in terms of bioavailability (given the iv potency), it's inexpensive enough that oral use still seems cost-effective. I might mention that this is definitely the worst tasting opioid I have ever touched my tongue to, in keeping with its caustic nature; so fucking bitter and gross. Just knowing u-47700 tastes like that makes me not want to throw oodles of into my body ~ lol! Since I snort things regularly and have access to other things, I didn't feel it was worth it to subject my nose (or my lungs) to more of this material, even though these roa's are clearly effective. IV really was quite nice and potent, and I could see using it this way from time to time as a couple-hour-treat. I should also try it orally sometime, as I think that may be quite nice. Hope my little bit of experience is useful.