Although not everything the pros do is something that should be copied or repeated by us mere mortals, the large majority of elite sprinters use Shimano SPD-SL or Look Keo pedals/cleats. Plenty of elite enduros and pursuiters use Speedplays, though.
Having myself pulled out of Keos whilst using straps (worn cleat) on a start, I think it might be worth considering a separate pedal/cleat system for the track, even if you still like to ride Speedplays on the road.