the Sporty does NOT have a third differential (normally part of transfer case) between front and rear drive shafts . That is why it is labelled a part time 4wd. In a turn, the front wheels run a larger circle than the rear wheels so there should be a difference out of the Tcase between the front and rear drive shafts that is handled by a third differential. In the SPorty, both shafts are FORCED at same speed hence this Tcase lock up condition should be totally avoided on dry surfaces. Never run in 4WD on dry surface except in straight line. Catastrophic damage to transfer case can result and has been described in this forum...I will search for the pictures and post them eventually.
THE advantage on muddy surface is that the front wheels WILL be driven (not locked up left and right though unless you do have a lock-up front differential) whatever the condition of rear wheels, even if the latter are hung up in the air with the rear differential bottomed on a rock. THis is the condition labelled 4LOCK on full feature 4WD transfer cases.