I've strung Babolat Pro Hurricane 18g and Technifibre Spinfire 18g in my Klippermate. Both were less than fun - lots of coil memory and not a lot of elasticity when dropping the wieght. I wasn't happy about having to string a racquet late last night, but I'm going out of town on business for the week and playing a tournament the day I get back, so it was either do it or gamble that I don't snap the string in my other racquet. I was very happy to find that the Luxilon Big Banger Ace 18 I was using didn't have nearly the amount of coil memory as the other two, and the string itself seemed to have a bit of elasticity. I thought maybe my clamps were slipping, especially given that the Ace is a bit thinner than the other two I used. Kept an eye on the clamps, and didn't notice any slipping. What's different about the Ace from a construction standpoint? Seems like I could expect some more playability out of the string given it's behavior going into the racquet. FWIW, they're all strung as mains @ 54lbs w/ Gosen OG Micro 17 crosses at 60lbs.