I have a full ZX-14 exhaust setup sitting in the corner of my garage. I was intending to put it on, but after I got it, I started doing some measurements, and the ZX-14 setup is significantly heavier, since it has two cans. I also noticed how long the ZX14 mufflers are. They are easily as long as the single can on the C14. So while it may look a bit nicer, it weighs almost twice as much, and if you remove the saddlebags, you'll now have two really long pipes sticking out instead of one. This is why it continues to sit in the corner of my garage unused.
I suspect they went with the single can on the ZX14 for the same reason, weight reduction.