For me, and where I live, protection from elements is more important than super quick access, and I say "super quick" because it really doesn't take that long to get into a roll top, for example, than other means of access. Besides, if the Talon were 20 or so liters there's not really that much to look through anyway.
Other than getting to my water, which I'd want in exterior pockets anyway, I don't need to get into my pack all that often. If there's something I might need quickly, like shooting sticks, I don't want it inside my pack, I want it outside (the mesh pocket on back off the Talon is good spot for that kind of stuff).
Personally, I think a good compromise is what I mentioned before; a pocketed lid over a drawstring closure, held down by straps with adjustable side release buckles, which would/could also compress the unit and hold clothing etc on the exterior. Might not look clean enough, but I'm far more interested in function than form.
