I can detect very little difference between any of the torrified grains and my wife's weird hippy breakfast cereals. I've used bulk puffed rice on occasion as an adjunct. Fruity Pebbles would probably make your yeast mutate.
A couple threads I read mentioned Grape Nuts as a great product to use.
Personally I was thinking of making the 3 grain cream ale and replacing the corn flakes with tony the tiger frosted flakes.. Figured it may give me more ABV as it has the extra sugar.
Now after reading all the cereal threads, consider barley, frosted flakes, and grape nuts