It's not so much content that I'm worried about, there's already quite a lot of content in Act 1, I'm more concerned about the max party level being 10.
If I don't diddle around too much and stay at least somewhat focused I can be level 4 (with enough experience for level 5) in about 15 hours.
30-40 hours seems a little short to me to go through all of your character progression in the game.
I have an unfinished save in DOS2 with 110 hours on it and I'm not fully through Act 4 yet.