That's cool! I'm glad to see magpies getting more attention.
I've never trained a herding dog, but I have both Indian Runners & magpies. I've had requests for Runners to use for herding, but I can definitely see some advantages with either breed.
1. Runners are faster, for sure--I don't know how important that is in herding dogs, but seems like it would be a factor. They're more agile too, so perhaps they'd be better for advanced training?
2. Magpies are slower, but also calmer. They won't freak out if your young enthusiastic dog gets a little excited.
Both are beautiful birds and good layers, so there's that advantage too. I love both breeds. I am thinking of thinning my flock down to one breed, but I really can't make my mind up which. I love them both so much.