Mondio ring is dominated by Mals, but the right GSD can do well in the sport. It is basically a combination of French and Belgium ring, with each sport making compromises and agreeing on the rules. You need an agile dog to do the jumps, so a small to medium sized GSD would be better suited for the sport. You need a dog with high prey drive and good nerves and don't want a defensive dog. The challenge for the GSD is that the sport requires a high level of control in the bite work. That is why Mals do so well. If you correct them and bring them down in drive, it is easier to get them back into high drive than after you correct a GSD. I would visit some clubs and ask around about breeders of GSDs that are doing well in the sport. There are kennels that breed predominately West German working lines.