Hi Clarese,
We switched from Concerta (72mg) to Vyvanse (50mg) last August for my 9 yr. old daughter. She had some pretty bad stomachaches for the first couple of days, but then they stopped. She is much more level on Vyvanse--up until 6-7pm which is a nice change from the Concerta. I also see more of the fun/goofy side of her personality on Vyvanse, which seemed to sadly disappear on Concerta. Also, she had bizarre rebound in the mornings with Concerta that we don't have with Vyvanse.
My 7-yr old son is on Vyvanse and has some ticking from it, but aside from that, it works for him.
We've also tried a host of meds--ritalin, Dytana, etc... For some kids it just seems to take time to figure out what is going to work, and even then it may change after a year. We always make med changes on the weekends so we can closely monitor possible side effects, etc..
Good Luck! Tracy