I've got a RPS fly and a Southbend kevlar sprung clutch. You still get rattling sometimes, especially when hot. I think the reason for having a sprung one is more to do with reducing the shock to the drive train than rattles. It doesn't bother me. I didn't go for the RPS 6 puck jobbie because the pedal pressure is a fair bit higher I believe, and I drive mine everyday in traffic. I've also heard you get a fair bit a chatter (i.e. some of the pucks grab before the others so you get a judder when engaging it). My Sountbend is a 6 puck too, so you do get this occasionally, but most of the time it's fine, and the pedal pressure is the same as stock (maybe a fraction higher).