The real advantage of digital is centering; ie.. transit time is measured at 60* of rotation under load, this means how fast the servo will rotate from full travel.
Digital servos will return to center faster and more accurately than non digital.
Torque is a different story...while 110-120 oz will steer your buggy fine, more torque (commonly found in faster servos)will result in less stress on the servo to do its job, thus the expensive servo will last longer under normal use.