Seems to be no trouble at all here. heading south at peak times there is a ban on unfolded bikes past Cambridge, but that's as far as I go so no issues for me. I have found the right train I think, that is direct to Cambridge North which is a nicer ride through Cambridge along the river, and doesn't stop at Waterbeach where people can be arsey.
I've regularly seen 3-4 bikes in every doorway vestibule with no problems at all, and easily 20 bikes exiting at Ely. Even had an interesting chat with the owner of a newish Canondale last week, about the merits of his new steed vs my airnimal as a holiday bike. His would look more complete of course once he'd saved up for the other fork.