1k on paid business ticket flying RNO-DEN-LHR last year. I think the fare was $9k so must have been a decent booking class.

Got to Den, boarded, settled in and our 787 to LHR went MX.
They had another 787 and pulled it around. Crew timed out and we were stuck in DEN for the night.

Called 1k desk asking to be put on the BA DEN-LHR flight the following day (space was available) or other connections headed east on other airlines and was told they cannot do that. All UA and the LH east bound flights to LHR were full (perhaps with rebooked GS?). I saw space on a UA DEN-LAX-LHR connection the following day and they moved me to that.

25k miles compensation plus full miles for my airfare basis as the rebooking meant I was allowed to exceed the 75k mileage cap.

As a 1K I’d say my expectations are they will get you on UA flights that are space positive regardless of fare class etc and that’s about it. UA has a lot of flights and options so that’s not bad but gone are the good old days when they would ‘protect’ you on an AA or other airline flight proactively in case of a cancellation even as a 1k. Those were good times to be a 1k.