I'm having this debate with myself right now. Well, not exactly, as I will absolutely take my DSLR with me (I'd regret not and am used to carrying it places; it's size doesn't bother me). But I'm so torn about camera bags (it's the one choice I just can't seem to stop worrying about). I have several bags and am trying to decide between a largish boxy one (that I have used at Disney before, but it's old and not as padded as it once was) and my large, multi-compartment backpack one.
I usually use my camera bag as an all purpose bag and not only put my camera in it, but also keep my extra sd cards, wallet (and tickets,etc), phone, sun glass case and a tiny bottle of saline solution, etc.
Both the bags will work for this, but neither is super comfortable and, more importantly, I worry about them fitting well with me on the rides.
I'm half tempted to try and buy a holster camera bag and take a regular backpack for the rest of my items (and pop my camera into it too, when necessary), but I don't know if I'm want to worry about 2 bags instead of just one.