I've been trying to hold back on switching to the stick option for the Vita version since I wanted to use the screen as much as possible. Going far to the Extreme versions of certain songs though, it looks like the stick is much better with regards to comfort and accuracy. Since I made the switch anyway, this should translate to my PS3 version skills I guess, only the stick movement is longer. I realized this when doing Envy Catwalk on Extreme. There is just no way I can complete the scratch notes with the screen without having my thumb go sore.
Actually using screen is still possible if you are familiar with it. I haven't try the analog yet, but on VITA it seems to be harder than on a controller.
On the contrary, it feels easier using the stick on the button is like pressing a button (if you push the stick up with your thumb). That might just be me though.
Probably not the right place to post this, but link scratches are really annoying. I just don't like the fact that you have to either get lucky or remember the pattern. So far I've failed about 3 songs on Normal with Cool Master because of this, and I usually play on Extreme. On topic: On the Vita I prefer to use the screen since I'm used to it. It doesn't feel right to me using analogs on it, but it's better on the PS3.
I'm used to screen but been practicing on stick lately. At first I kept accidentally swipe the screen and nothing happened. Now I can use stick easily since using screen cause me to shake my vita at the same time while spamming those star (Senbonzakura or Battle of Kagamine). Imo, I prefer stick.