Ive got one mate hes only 20 month so i cant really tell yet but hes got loads of drive (abit too much at times) he is the only one ive ever saw work so im no expert but hes very fast for a big dog, not excellent at turning on hard ground, staminar is ok but he would run till he drops dead so i have to keep a eye on him abit more than my other dogs. If theres anything else u want to know ill try and help u atb