I found a trip report for RU-28306. It's translated from German.
"04/05/2017 - 11:16
I just sit with Swim together and have us about 20mg internasal gesgoennt. It is a 1/25 Mannitol Mix.
RU-28306 looks like crystalline lsd, very fine-grained and of a gray color. Nasal burns it a little and is rather unpleasant to pull compared to other tryptamines.
12:10 / first application Nasal 20mg, up to increased pulse and light bodyload is still nothing to trace.
12:45 / second application Nasal 20mg. We drive it outside, easy Mindtrip feasible. A feeling of weightlessness.
13:40 / we believe the peak has reached: very sedating, body movement is very straightened, hardly optical changes, the time passes rapidly. Sexual pleasure is enhanced.
We have tried to keep us awake by all means, but then they have probably kicked off shortly after 14 clock. At about 5:00 pm we woke up on a bench. We have expected quite a different effect, especially to the peak, it is more like Acid. But no, it's DMT like. I'm sure I had planted lentils and clay floors from a stone quarry. But well, we've only got to the first bank on the way to the quarry.
Salue"
"26.04.2017 - 15:25
Well, have now no after effects. But will never consume it, since it is simply too uncontrollable. Had various attempts where it had turned out that one sleep. Afterwards active third cared for and two phases determined. The first is a very restless sleep, then you wake up and walk to the fridge (usually without consciousness) and then sleep again. This time a distinct Rem sleep phase can be seen, so a deep sleep.
I asked my vendor not to drive it anymore. It has little spiritual potential, rather so ne Rape thing. Swim has labeled it differently and placed in his hole to the top. So that any stranger first pull the A card. Had to show him also only nen bird .... With Ru-xxxxxx is not to joke."
20mg of 1/25 is 800ug dosed twice for a total of 1.6mg which would suggest this is highly active but with unexpected effects, very possibly due to its uncommon structure it might be hitting side targets before the 5-HT2 sites are activated sufficiently. That report did not sound so good but i feel it still needs a confirmed NMR and more bioassay. There is also the posts on the bluelight thread of another user (with photos) showing and describing the exact same substance and said they felt a +1 or +2 level just by handling the substance and said they would increase dose to 400ug and report back but has not posted back for two months.
https://www.eve-rave.ch/Forum/viewtopic.php?t=50725