I do not own any labocca but i bought it as well just to be safe in order to save shipping in case i bought the wrong one. I’ll try to find and let you know if i did. I recently moved so its in a box somewhere.
I have recently received an ORS2 with the adapter for smaller inserts and have done a lot of testing with what is compatible. It should be noted that there is a toothed track that stands opposite of the wall part that is not shown in Mosiac’s pictures on his site. The teeth are rounded and do a good job of holding onaholes in place without any additional restraint.
The sweet spot for compatible onaholes is about 7-8inches in circumference. Skinnier ones at about 6inches around wont contact the sides of the holder and at about 9 inches, they are too big to fit inside. YMMV depanding on the materials the hole is made of. A softer but bigger onahole might fit where a similarly sized onahole of a harder, less squishier, material would not fit.
All I do to get appropriately sized holes in is feed it up through the bottom of the holder while it is attached to the OSR2. I then reach in from the top and pinch the top of part the onahole, drag it up to a good height and am good to go. I have tried this with several different onaholes and havent damaged any from rubbing on the track that holds it in place.
There are a couple of sharp corners at the top of the rounded part that supports the other side of the onahole opposide the toothed track. If these were changed to a small radius, people might not poke themselves on it. Someone would really only come into contact with the pokey bits when inserting the onahole and not while actually using the OSR2 so its not a big deal but it might be nicer to have those edges rounded off.
Overall, I would say that the adapter works really well. I have never had an onahole slip even when the OSR is pressing down with a decent amount of force.