I've gone to Crystal Palace 3 times in the past 3 years, and never once been asked for any proof we actually had an ADR. They seem most strict at Hollywood Studios, and also the least efficient at getting people in early.
I strongly recommend getting there earlier than advised, as I've had an 8:25 ADR that we were seated for at 8:05. It is first come, first serve that early it seems.
I've also never not been out of breakfast before 9am. I'm not sure what people are doing that always takes them so long. It is buffet, your food service begins immediately. Your only delay is if you hit a bad cycle where a character is about to get to your table, you get the parade, and they go on break after. That can be a 20 minute death blow, but short of that we always get to see all the characters in 45 minutes tops.
Even if you have to miss 1 character, leave the restaurant no later than 8:55 as they let people in early often. You line up just beyond the castle and then proceed to Dumbo. Being on the 1st or 2nd ride of the day is a huge time saver even on very low attendance days.