My SWCAH son is now 17yrs old. He had to switch to Prednisone when he was about 10yrs old, because we couldn't get 5mg tablets of Cortisone any more. He did fine with the switch, & evidently his Endo did a good job figuring the Prednisone doseage for him. I was scared to death to make the switch, because just like you, I didn't want to mess with a good thing! But it all turned out well, and he has done fine. His Prednisone dose increased as he started puberty, then took a big jump when he was definitly well into puberty, and has remained the same dose for the past three years.

Good luck. Have faith and give this a good shot, but never stop trusting your instincts!