We took Toby out with his last night, as it arrived yesterday, and my OH tried it again this morning. I can definitely see the advantages when he is walking well. However, he is devil for biting his lead (which we are working on), and because the lead fastening is at the front, it is far more accessible for him to bite! My OH just came back in from walking him and said, I'm not using that again until he stops with the lead biting - he's a nutter!
I'm in the process of modifying a lead to put a short link of chain in the lead, as per some suggestions on COL, as that should be less tempting.