We switched from Concerta to Focalin because it was supposed to boost appetite and our son needed to gain weight. We never did see that side effect, but I think that was mostly because our son just doesn't like to eat.
The biggest drawback was that our son processed it WAY too quickly. It was out of his system by lunch time (about 7 am to noon) -- NOT good. For that reason, we switched back to Concerta. It worked basically the same as Concerta when it was in effect, though, but just didn't last long enough.
DS just switched to Focalin XR 10mg about a month ago. He was previously on Concerta 27mg... which was working great for a while then just seemed to stop. Dr. didn't want to increase the dosage b/c of his size. (6 1/2 and just under 50 lbs).
Anyway, I have seen nothing but good with the Focalin. It seems to start working faster in the morning, which is great b/c I know it is working by the time he is at school. Also, the "come-down" time period, is WAAAAAY smoother than with Concerta. Concerta he literally turned into a mad-man, getting very angry, etc. Focalin, he is still definitely noticable that he is coming down, but less "violently."
He is definitely more agreeable and cooperative when he is on it. AND he seems less mopey. I guess I shouldn't get too worked up since it's been only a month.
I have a friend whose DD was on XR 10mg too and was having a rapid heartbeat so they switched her to Concerta. Friend was bummed b/c she was very happy with the results they were seeing with Focalin, but DD's health is more important and Concerta seems to be helping.
DS (10 years old, 65 #'s# takes Focalin XR 10 mg.