Because I feel that MS4EX has a better traditional feel when doodlin and MS5 is much more of an Illustrating program... and I still prefer using MS4EX to organize my files and artworks using the "Story File" option, which is kinda missing in MS5
Huh.. interesting. Good to know. I have yet to see Manga Studio 5 in action. I'm happy with Manga Studio 4 still so I don't think I'll upgrade any time soon, but it's good to get insight from you! I really like the story file option in MS4.