changed status from beta to omega to reduce updates, console stuck on update now 0x8B050033...

If you're an Xbox Insider then you will get more updates as compared to others. Even as an insider there are 4 different rings - alpha, beta, delta and omega. Being in alpha ring will result in a lot of updates, and number of updates goes down as you reduce
your level.

If you do not want frequent updates you can unenroll from the program.

In my understanding the Dashboard experiment, A, B, C selection, is totally random.

As "Both consoles say their OS Version is (19h1_release_xbox_dev_1911.191028-1335)" your consoles are either in the Beta or Delta ring.

Both those rings and Omega ring are getting a preview update News release notes Beta Delta Omega
Insiders today, which you can manually start or wait until it becomes mandatory.

After you do the update, if you want to change rings, it will be the perfect time to change as all those rings will be on the same release. Subject to eligibility.

Thanks HS, I have been able to move on from the green screen but now it seems stuck on an update? I have the console picture on screen showing the update status bar but it gets to about 70% through and goes no further. Any suggestions?

Hi, it depends what ring you are in. Currently there is no insider build for Beta, Delta and Omega rings, this means you will be on the current public build.

So I was in the beta, but I would like to take my console from the insider and not receive more updates and the insider hub app is not getting my console off, it just stays on hold.

Instead of leaving the Xbox Insider program as one Ambassador has suggested you can drop down to a lower ring which receives much fewer updates. For example if you are in Beta ring drop down to Delta or Omega. The Omega ring receives the fewest updates,
usually just before it is released to the general public. This can be managed using the Xbox Insider Hub on your console.