Adults will nail you just as much as kids, kids will usually be more physical and louder though (more disruption), but adults let you know via (especially) facial expression.
At least through my findings, though (through various shows I've watched and chats with some fellow magicians), kids may be more disruptive if something goes wrong, but it's also easier to get back the attention of kids than adults.
Sneak, you obviously don't do a lot of kid's shows. I have seen adults be amazed at certain effects but the kids saw thru it instantly. Hey, that's happened to me, not often but it has.
As for the last sentence, you have no idea about kids. If you lose one kid and he gets bored. You're toast. The bored kid will start to disrupt your show and that's all Folks. You MIGHT, if you're REALLY LUCKY get back one or two of the kids but the rest are gone and they will cause enough havoc to destroy your show.
Some of the people here remind me of one time I was in clown doing a restaurant. This one lady said "I used to be a clown>" So I asked her where she went to school and her answer was "Fairfield High School." Then she told me "I have never had a kid afraid of me." That told me she not only didn't know what she was doing but she was also a liar. Same here when someone says "I have never had a problem with kids losing attention."
Your last paragraph shows your nature once again, Pad! The hate that you bring here to so many makes one thing seem obvious, you must have alot of problems at what you do despite your claims otherwise! But, hey, that's just my opinion.
To clear up one matter you brought up, I have about 100 kid shows under my belt. Maybe not as much as you, don't know, don't care, but enough to warrant responses here.
And to another matter, if you don't follow up immediately, then yes, you have lost the crowd probably. But a quick reaction can fix the problem. A magician should always have something ready in the event something goes wrong somewhere in your show. What I have done is to have a standby effect that that can be used at any time and it uses multiple spectators so that as you bring them up (and they pretty much all want to go up), their attention goes back to you and the show. In about 2 situations thus far, it has worked 100% of the time.