I ride Time Atac XL, they have less of a platform but predictable engagement and release. I am a big fan of Time for quality and durability. No experience with the Z model but definitely like my XLs which appears to only differ in the amount of platform, the clipping mechanism appears the same.
Amanda
2011 Specialized Epic Comp 29er | Specialized Phenom | "Marie Laveau"
2007 Cannondale Synapse Carbon Road | Selle Italia Lady Gel Flow | "Miranda"
You don't have to be great to get started, but you do have to get started to be great. -Lee J. Colan