There are two basic categories of speed flying wings - proximity and speed soaring. You will notice in going through the different brands above that we have listed both types offered by each manufacturer.
Proximity wings are meant for going downhill, fast. Their design is more like that of a high performance parachute, with cell counts in the 16-22 range and aspect ratios less than 4.0. There is less lift created by these wings and therefore it is easier to fly close to terrain without the wing trying to constantly fly away from the mountain. When you come out of a hard turn, a proximity wing will continue to dive. These are the fighter jets of speed flying wings.
Speed soaring wings allow pilots to fly for extended periods of time in stronger winds. They incorporate design traits of paragliding wings, with cell counts ranging from 26-44 and aspect ratios greater than 4.0. The result is an airfoil with good lift. Speed soaring wings are capable of very quick maneuvering, and have a tendency to climb out of steep turns. These wings will give the pilot more of the feel of a hawk swooping along a ridge, diving and then climbing upward to do it over and over again.
Ultimately a pilot would own both types of speed flying wings to be able to enjoy all sites and conditions. If you are going to own only one wing, it is worth noting that you can do some proximity flying with a speed soaring wing, but you really cannot speed soar a proximity wing unless the winds are howling.