RockShox's superlight, flexy and unashamedly race specific SID (Superlight Integrated Design) ain't no tough trail fork, but he is the most successful World Cup XC fork ever, so we couldn't miss him out. Dual (positive and negative) air springs let you set it up anywhere from 'move once a lap' stiff to surprisingly plush comfort. The PopLoc Adjust lockout remote is a joy to use and also has a thumbwheel for changing 'Floodgate' breakaway threshold on-the-fly.
Regardless of set up the super skinny crown, legs and minimal lower/upper section overlap means suspension action does get choked by massive fore-aft flex when braking or hitting bigger trail trouble. This means you're best hopping over whatever you can, and at under 1500g it'll certainly make your front end come up easier. Even the rebound adjuster knob is removeable to save a few extra grams.
Steering vagueness will come as a shock if you're used to a burlier fork, although you'll get used to turning earlier and harder to make things happen in time. In short, don't be looking at this fork unless you're the skilful, skinny weight watching whippet it's designed for, in which case it's a great value race fork. If you want tougher or more trail orientated forks, leave poor SID alone and get a Reba.