Did you like the Highlife? Why, or why not? Are you looking for something similar or different?
Considering stiffnesss and stability the Highlife is comparable to the Flag. So if you liked the Highlife you may as well like the Flagship especially if you aim to ride a lot of fresh snow; its huge rocker nose delivers great float in deep pow. Carves great, very fast base, but it's also an unvorgiving plank in moguls (at least my '13 model).
Don't know the Rossi.
"Yeah... no, that's not clumsiness, that's just being topographically challenged" ~ Noreaster