I have just jumped to the Delta ring. I would like to try the new dashboard and OS update...

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.

I am currently trying Delta ring. I will report here if it helps with crashing in late game.

UPDATE:

I was able to finish the game that was constantly crashing after updating to Delta ring release Xbox Insider Release Notes - Delta (2208.220715-2200) - Xbox Wire

If Omega ring has same fixes, then hopefully everyone will get this fix soon.

I will continue testing with Delta ring with all addons enabled (currently have extra civs disabled) with new game on huge map.

As an Insider I've just gone thru 3-4 updates in the last week, 1 30 minutes ago, and the dashboard has had some changes to location of Tabs (twists) for Gamepass, Mixer, Community and Store.

Also a bug was fixed that was quite annoying and it seems a lot more efficient and responsive.

It is being tested by Beta and now Delta rings, next will be Omega and then after that GA (General Availability) will get released I assume sometime in the near future.

So prepare yourselves. News for Beta, Delta Insiders Update provides further details.

They've selected a few in the
different rings that are testing the new dashboard as far down as Delta ring, actually. But not everyone.

No new information, Delta. They are still working on it, though! If I get anything new, I will be sure to jump in here to update you.