This. As much as I adore Quinn and I in no way regret her, I have learnt oodles of stuff in the last two years that I so wish I knew two years ago. I started her wrong, tried to keep her head calm and taught her lots of stuff but didn't give her an outlet to go nuts with me. So ended up ith a dog that is very reactive to other dogs working and is constantly looking for other places to get stimulation. She's improved a LOT since the problem first cropped up over a year ago but I don't know if I'd ever do something like flyball with her just because of her head explosions. High drive dogs are fun but they take some getting used to. I can't wait for another one but I wish I wasn't sorting through my previous mistake now (Quinn's been out of agility training for well over 8 months already and I'm just re-starting her foundation again now) I suggest starting with the dog you've got already aswell, Buster I would have loved to do agility with but he's always been incredibly DA, extremely anxious in public and has HD to boot so he probably wasn't ever going to make the agility ring, still hanging out on him being a Rally-O dog though.