I spent a ton of time researching this choice, and it was a tough decision, but Marzocchi garnered the win overall. The RockShox SID was a close second. While the SID is lighter than the Z2, I was astounded by the Z2's massive weight advantage over the stock RST part.

It'll be a long time (if ever) before my MTB skills even get close to taxing the performance capability bottled up in this gorgeous package. See the reviews on this killer part at mtbREVIEW. In addition, check out the Z2 X-Fly Tech Manual and Tuning Tips PDFs from the Marzocchi website.