Tough questions to answer definitively. A single Giant Fat Glider is more substantial than two Little Fat Gliders. With the Pioneer speakers, if you're going to have Gliders on only the front side of the Cabinet, a single Giant Fat Glider would be a good choice. You'd have more vibration-absorbing "beef" to accomplish the job. With a pair of small Gliders, however, you'd be supporting the corners where the cabinet is likely most rigid and strong, and with the isolation more evenly distributed. So, I don't think you'd go wrong either way.
With four Little Fat Gliders, you'd have the speaker completely decoupled and isolated from the floor, whereas with two Giants on one side only, you would not, with vibration and isolation uncontrolled at the back of the cabinet. Four Gliders provide fuller distribution of the cabinet isolation as a whole and would most likely be the better choice.
Herbie's Audio Lab