Ray,

"actually a strike indicator does not hold up the fly, the fly should drift naturally on or near to the the bottom."

Depends on where you set each. If the water is 3 feet deep and you set the indicator/bobber at 2-1/2 feet, both will hold up the fly. If you set either one at 4-1/2 feet, they will both have the same effect on the fly's drift.

Allan