you've been riding the cbr so it's only natural for you to prefer the Ninja. nothing wrong with that though, it is a solid bike with some nice features. ABS, Slipper clutch etc. i like the looks as well.
i've been riding standard bikes for quite some time so i naturally prefer the upright posture, plus, i dont think my wrist or back can handle being leaned over for extended periods.
but yeah, seems like the 390 is just a 390cc engine in the Duke 200 frame.