As stated in the original post, IrisVR seems to do a good job. I've been playing with it on the oculus quest 2. See link below. I don't know how it is accomplished technically, but it seems to always work well in areas that Enscape flickers.
I feel like this touched on a subject of the importance of clean models. Once again, totally in agreement. I do encounter the flashing more often than I would like to admit. Sometimes it's a linked element, sometimes it's a the vertical walls of a bulkhead interfering with the ceiling, sometimes it's the trim on a bad door family---but it happens.