Funny you should ask: this weekend we bought a Gentle Leader for our Aussie, and fitted it for him in preparation to use it--but yesterday my DH managed to lose both of our 6-ft training leashes at the park! Arrrgh! Now we gotta go shop around for new leashes....

Once we get things going with that GL, I'll let you know how it works. We chose it over the Halti mostly because it looked similar, but a little better made. It's got good introductory training material in the package as well.