Huh. Since I start my chest workout with inclines, I use more weight than the flat. If you want a more "shelf" look, you'd do inclines more. Your upper chest development accentuates shoulder development.
So, you see, whatever you start with, you'll do more weight than your next exercise.
As to db vs. bb... do what you like to do. Let me say, it's a lot more impressive seeing (and doing) 125# db presses than 315# bb presses IMO. It also saves my shoulders. Plus, getting a bench for bb isn't as easy as getting the 125's. Who do you see using those? Almost no one. How many people do you see waiting for a bench? Alot. Simple economics.