One comment about using a forum posting for channel review. You encounter a problem as the postings age and the channels change. On another forum I read there is a post about Biodiesel locations. It's an enormous thread with hundreds of posts. The problem is, the vast majority of posts are no longer accurate. I see the same issue trying to evaluate Roku channels. Someone might trash (or praise) a particular channel, and 6 months down the road something changes and the original review doesn't reflect the current state. Even worse, the channel may go away, but the posts remain and you have to slog through them to find something. There might be multiple postings about the same channel, perhaps separated by dozens or more posts, so you wouldn't seem them all together to make a valid judgement.
I'm not saying at all that some method of channel review would be valuable, because it would be. But keeping it valid and up to date would require someone dedicated to maintaining the postings. That means someone with forum admin rights. To my knowledge, Roku does not have any non-employees with forum admin rights. And I have my doubts they would dedicate a staff member to maintain something like this.
I think for something like this to work, you need to track each individual channel individually. Considering how many channels there are, using a forum such as this isn't really practical. Instead, you would need a web site that has a database back end that allows searching by channel name, genre, pay or free, etc. If Roku would be willing to provide the resources to host such a site, I'm sure that volunteers could be found to maintain it.
I suppose you are right about the problems in maintaining channel posts on the forum, and I also suppose there is no really good solution to that problem without the ability to have a dedicated forum for that purpose and an active effort at maintaining it. That seems unfortunate to me as I believe that any such effort would be actively used and read and be of real value to readers. I, for example, went through the process of adding the SyFy channel to my Roku (I still have cable and will continue to have it until my contract ends) and activating it, only to find that all of the stuff that I thought would be on it, is not. Series that were broadcast on the SyFy cable channel (Eureka, Babylon 5 and others) and movies (the new Star Trek, Butterfly Effect, Independence Day, LOTR, The Hobbit and others) are nowhere to be found on the app version and I realized that it was a waste of my time. I could communicate that to others if there were channel reviews.
Still, as I said, I guess you are right and we each have to find out what works and what does not work for ourselves.