Congrats to you and Summer! Good Job! Hopefully she'll settle down with that screaming. 
Yeah, Summer's dog reactive. It can be a challenge but she's not *too* bad. In our class we have 2 DR dogs and a DA dog and we manage just fine. Two dogs have decided they want to kill each other so that's always a challenge. They were okay until an offleash playdate, not during class obviously, where the JRt got run over by the lab. Now the JRT has a vendetta against the lab so those have to always be separated. Our class is mostly on a leash until we're working that dog. So we go out and wait our turn, then when you're in the fence you pull the leash off your dog. Summer is very good though and I tend not to hold her leash if we're just waiting around. She'll just sit there and chill fine until it's her turn.That sounds awesome - I wish you had video. Honestly though despite the major agility accomplishments I think the no-snark day is extra sweet.. because I know what that feels like!
I have a question, though, because from your posts it seems like Summer is a bit dog-reactive.. how do you deal with it in offleash classes? Did her focus get better with time? Marge has snarked a couple of times at fast moving dogs and I haven't really tested her being offleash with other dogs training hard offleash in very very close proximity.