Yep- we always do late breakfasts(not morning people!)I have been to Chef Mickeys 3 times for breakfast and it has always been good.The food is still fresh and replenished throughout.I would recommend it.
We do this frequently. I think the latest times are in around the 10:45 timeframe. Food is still the same high quality and you can generally get more character time as the restaurant begins to clear out (as long as they aren't doing a lunch session - lunch sessions generally only occur during peak periods and/or free dining).
We had a late breakfast there back in February and it went well. Our reservation was for 10:35 or 10:40 am and we were seated promptly after checking in and having our picture taken with the Chef Mickey statue. Food was replenished and all 5 characters made the rounds and spent decent amounts of time interacting with the kids. We were done around 11:30 a.m. and off to the MK for the afternoon.