Road sprinters are a picky lot. They need to ride all day in the slipstream of others to get their shot at the final 200 meters and a ballistic shot at glory. It should be little surprise that this is the wheel that fast men like the Manx Missile, Mark Cavendish, gravitate towards.
The wheels are saving you energy every pedal stroke, and with the new 188 rear hub, they're laterally stiffer than ever, an advance that Cavendish directly collaborated on, testing out prototypes for months. He used to be so picky about his wheels that he demanded tyed-and-soldered spokes. He no longer needs that.
The wheel is also a great time trial and crit setup. The wheels are light, and, the Firecrest shaping makes this 82mm deep rim faster than disc wheels in certain wind conditions. The plus is that they ride better and are much easier to handle in crosswinds. The wider body cradles the tubular tires better, more gluing surface, more supported weight, so it's both harder to roll the tire, and they have less rolling resistance on the road.
Your ability to handle crosswinds is probably one of the biggest factors in choosing a rim depth. The great thing about the 808s is they handle like much shallower wheels. The firecrest shape is the secret. The blunt end and flattish profile not only reduce low pressure zones on the leeward side of the wheels, but through smart tuning, Zipp was able to move the focal point back, so that steering would be easier—which means less attention needs to be paid to riding fast and less arm strength needs to be used to hold the wheels in the direction you want them to go.
The wheels are delivered with quick release skewers and brake pads. Zipp strongly recommends use of their pads on their rims and warns against using carbon-specific pads on aluminum rims.
The Zipp 808 Firecrest Carbon Tubular wheel set gives you an edge on everybody.