Seams to me, the lack of a 3D gimbal is the reason Spark doesn't have this feature. DJI couldn't take out the jittery yaw motion, entirely. All DJI drones have very high I-gain, which was always the reason for 3D gimbals. High I-gain yaw, improves straight line video but degrades yaw effects.When a quad copter yaws it increases the speed of diagonal props, when the copter compensates for wind it must correct induced yaw by checking with the compass, any variations will be seen on a 2D gimbal . 3D gimbals operate independently on the Z axis and softens the affects but the yaw correction is unavoidable on quadcopter. Hex and octocopters have less of this effect because the aircraft doesn't require pitch and role correction to anywhere near the same degree when yawing.
DIY builders often get to this point with 2D gimbals and realize it isn't going to work for some tasks. DJI will sell you a hexacopter setup that will do this circling effect but it wont fit in a backpack. On the other hand, Spark can do many things a 800mm hexacopter can't.
Cheers