Hi Jo,
As you know, I've always been against clipping, but of course, that's just my feelings and my situation. As we have always discussed, each owner has different circumstances, and they are more able to decide to clip or not. To answer some of your questions, a bird with clipped feathers probably has a better chance of breaking a cut feather than one whose length is full. Clipped feathers, especially the normal clip which leaves stubs is not flexible like a full length feather, and with that, any time that feather is bumped or hit, it breaks instead of bending like a full length feather would. As you probably remember, Chibi had so much trouble with broken feathers because there was none left to help protect the new feathers growing in, but then again, his clip was so severe, it's a wonder he ever regrew flights.
Relationship..
After he finally regrew all his flights, he had a hard time in the beginning of learning to fly, and his confidence level was very low in the beginning, but as he learned his ability to fly, he finally had become a good flyer. Prior to his flighted condition, he was just a normal acting bird, and he depended on us to take him everywhere. Once he could fly, because of his confidence and ability to fly, he would come to us whenever he wanted to, or fly off the same. Overall, I'd say our relationship became better, because he realized he was no longer a ground-pounder, and he was definitely happier.
Training..
No training of any kind, other than what was safe and what was not. We have always permitted all the kids to decide when they wanted us and not the other way around, however it was routine for Emi or I to go to the cage or bird room and select whoever we wanted to be with us. In many cases, we didn't have to ask or even hold out a hand, they would just hop on.
Accidents..
Yes, we've had accidents, one very serious which led to Chikara's death, and a bunch of accidents that caused broken blood feathers with Chibi, and to some extent, Ginger. Most accidents are things like flying into windows, walls, and most times, all this happens during a panic. After everyone learned they could not fly through a window, the occurrence of window strikes has dropped to nil, however a panic flight does still cause some of them to occasionally fly into the windows, but not hard enough to cause any injury. As for flying into, or dropping into stuff in the kitchen, no, but they have all learned the stove is off limits, even though many times they will line up on top of the china cabinet and top of the refrigerator watching us cook, just like a bunch of vultures

The most "dangerous" of all the kids is Missy. Any time cooking is going on, she can become hell-bent on getting right in the middle of whatever is going on, and loses respect for the hot pans and stove top, but when she gets like that, I normally will take her away from the stove area and have at times, locked her and the others in the bird room. Just about all of them at some time, accompany us to the bathroom, and it seems none are fascinated with the commode. The ones that normally go are the same ones we take to the shower with us.
Coming on cue..
A few of the kids will find places to hide, and sometimes during a panic flight, they will get into places we don't normally permit them to go, like the spare bedroom, or our bedroom. Pixie was notorious for doing that, and when you call for her, she'd not make a peep. I think between Gizmo, Ginger, Pixie, Cappy, and Shelly, they are the ones who would remain quiet while we search the house top to bottom looking for them. They can find places in plain view to sit, but it's one of the places you don't normally look for. I've almost panic attacked myself when I thought someone had somehow managed to get outside, when in fact, they were just sitting in a non-normal place!
Poop..
Really, it's a non-issue, because we know they are going to poop wherever they are, and the places they perch are the places we clean regularly. Many, many times per day, we go on poop patrols looking for the stuff, and given that we know most of the places they wander off to, that's where we look. Of course, flying poop is a problem, but you just expect this kind of stuff and deal with it.
Mischief..
Not really. They can get to more places, but I had Missy and Gizmo destroy the edge of the patio door when neither could fly that well when they were both really youngsters. Now, they attack the cabinet molding and anything else where they spot a little speck or irregularity on the wall, or a piece of wood. I guess this falls into the same category as some of the other issues, we expect it and deal with it while trying to discourage them destroying the house or their room. As you may have seen the picture of where they stripped the drywall paper off an area in their room, and started chewing into the gypsum making a pencil sized hole. It does not take very long for them to destroy something either. Those sharp little beaks can chew into stuff you'd not think would be attractive to chew on, but to them, if it's not steel, iron, or some other non-chewable substance, then it's fair game
