My wife used to herd competitively with a 42# shelty, some dogs just get big. Judges would look at the dog and ask her what it was. My dad had a GSP that could put its paws on dads shoulders and look him in the eye. Some thought he was a Great Dane cross but the rest of the litter was average size.
Deaf dogs can work well, when my AWS went deaf I used a collar with vibration mode to alert her to look for my hand signals and tI would wear bright jacket and hat so she could find me easily. You could see her bounce up out and high grass to check to see if I wandered off.
