I would assume the dosage of Pulmicort (same number of X's daily, same amount) would remain the same whether you are using a nebulizer or inhaler to deliver it. Some studies show that children especially, receive more of the medication to their lungs with a nebulizer than with the inhaler, even with a spacer. As the other poster stated, convenience would be the main reason for changing the delivery method. (although side effects, too, can vary according to the delivery method)
As for the comments listed online in regards to pulmicort, I should have noted that most people don't go online to praise such meds, they go out there in search of information because of problems they have had with it, so obviously when reading sites like the one I referenced below, you are going to see the negatives outweigh the positives. I simply wanted to show that according to many patients using this med, behavioral changes are apparently a problem for some people. I think it is important to look for side effects to meds that the drug companies don't list. The last time I checked, behavioral changes were not listed as a side effect of Pulmicort, but it would appear that it IS a disturbing side effect for many people. I would however, assume that they are in the minority.