That flash backpack can be turned inside out to look like a stuff sack, right? I say go for it, and if it gets to annoy you, turn it inside out, put the stuff back in and strap it on top of the other stuff already on your rack. For some reason getting rid of the rack just makes me a little nervous. I'd like to have it there, just in case I needed it, but then I know you're all about ultra-light so maybe you'd prefer to get rid of those extra 3 pounds or whatever. I'd say give it a try for a short one and see how you like it.