The UltraSport 254 has a disk loading of 1.52 lbs/sq-ft. and a descent rate of 15 ft/sec. It is also claimed that the Ultrasport has enough inertia to autorotate to the ground then lift off and re-land.
Tip weight: 2 pounds.
T/K formula is 2.5 seconds.
Incidentally, it uses the VR7-B airfoil, which you are considering.