Mixxon gave some of your answers... though I think v5 is available for new customers too? There's a price for new customers at their site anyway. The full EX version won't be out till summer though.
from the videos I've seen and things I've read the version out right now (not the EX version) has everything EX4 has except for a few things: story mode and perhaps some of the 3d handling?
But v5 has coloring on par with photoshop, pencils on par with sketchbookpro and has all it's inky manga studio goodness!
this dude gives you a NICE long look at the differences... it's a long video but if you're into manga studio the way I am you'll dig it.