I'm pretty firmly in the "go smaller" camp when crisp handling is the issue. The shorter wheelbase and the positioning of the rider's weight centrally or a bit forward l, combine to make a bike reactive to more subtle input and more "flickable".

That's all assuming the basic geometry is right, of course. I don't know anything about the Sirrus Comp or how aggressively the OP rides, but as someone pointed out above, just moving from the Giant NRS to the Sirrus alone should satisfy the OP's needs, irrespective of size. Still and yet, I'd advise sizing down, especially for dashing around the city in a sporting mode.