Yeah, level to level difference was out of control in DOS2. Assuming they stick to D&D rules, shouldn't be such a problem, right?
A well-optimized party can fight two or three levels (called Challenge Rating in the tabletop) above their weight class, but if you give away more than that you're in deep shit. Things get looser as you level up and can power game your way ahead of the challenge curve, but especially at low levels it's fairly easy to get wiped by encounters that aren't even supposed to be particularly deadly.
If they do something like front-load low level characters with extra hit points, which was something 4e did that I think they should have kept, it wouldn't be as bad.
