Zapp,
At the world level, it's quite unusual in match sprints not to use straps, and either 7400's or SPD-R's rule the day. Pretty much the same for team sprints. In kilos, about two-thirds of the riders use straps, and SPD-R's are particularly popular for their aero design. In pursuit (both individual and team), toe straps are quite in the minority. At the LA World Cup, a couple of us were right at the finish line and while riders were setting up, were photographing bar setups, pedal setups, and anything out of the ordinary. We got images of every rider in the kilo, team sprint, match sprint, and pursuit (at least on our side of the track), and the images confirm these observations. The Brits weren't in evidence at the event (except for Jamie, who didn't last long), and they tend more to no straps or single straps, in either case on SPD-R's. Again, pedal and strap usage are a different game on the massed start events -- kilo, match sprint, and team sprint have practices unique to their disciplines.