Where are the exo-Oort Clouds? Perhaps they need to be renamed.
Having read through the Wiki reviews on the hypothetical "Oort Cloud", the theoretical "Hills Cloud" and "Comet", it would appear they are written by different people with somewhat different views, no surprise there. But for me, the biggest surprise was the description of the Hills Cloud.
Without being too expansive, the Hills Cloud and Comet reviews put more severe constraints on the distance of the presumed Oort Cloud's outer edge, of which the Hills Cloud is supposedly an inner part of. These distances range from 0.79 ly to 3.16 ly. Reading between the lines suggest the author of the Hills Cloud review doesn't put a lot of confidence in this farthest limit. The review on "Comet" was similar in this respect. The Oort cloud review states right off the outer limit is 3.2 ly. Clearly a difference of opinions. What is most striking in all of this is the proposed density of the Hills Cloud, and that real objects appear to have been spotted there.
The Hills Cloud review suggests that it is likely the source of most comets, and even supplies comets to the presumed distant spherical Oort cloud. The Oort Cloud is hypothetical in that there is no direct evidence that it exists, since all comets could have arisen from a "stand alone" Hills Cloud and their trajectories modified by asymmetric out-gassing, the gas giants and the sun (etc?). The author of the Hills Cloud paper suggests that the spherical Oort Cloud is so weak and tenuous that after billions of years, it could only be maintained today by comets from the Hills Cloud. For me at least, that provides a good reason to dispense with any spherical Oort Cloud and go with Hills. Unfortunately, the extreme distance to the main body of comets in any hypothetical spherical cloud likely eliminates observational confirmation any time soon. Lacking that, it will remain hypothetical to some of us at least.
Something else I got out of the Comet review - there are a lot of hyperbolic comets previously observed. Having never studied this, I only became aware of the feature when the two interstellar objects appeared. Since they were observed with hyperbolic trajectories, it was noted in the main stream press that this defines them as leaving the solar system and never coming back. So with my extremely limited knowledge on this subject, how can all these other comets have hyperbolic orbits and yet none are considered interstellar objects? Must have missed something somewhere. Hoping rod can fill me on this, and the below.
One strange observation that needs to be addressed is the longevity of comet out-gassing. I might be hazy on all this data overload, but I believe it reported that short period comets last longer than long period comets. It would seem to me that the opposite would be true, but all depends on the amount of out-gassing per orbit, and the nature of the comet itself perhaps. Does your more than considerable knowledge of comets agree with this, and how could such a thing be true?