When i flash the Spain one from 4.3 throught Odin my apps and everything remained the same as if i just flash a minor update.Even the homescreens and widgets.I was waiting a format(like the i9000 i have) but no.By the way the only stuttering after the update is from the launcher in portrait.With apex everything is superfast and smooth and the tablet ui it has(just tick the box in the options) is very nice.i also saw a 1500 more points in Antutu.