I wonder how many here have opted for a Camelbak or similar packs? I'm assuming you have many bikes with many different configurations. Some with racks, some without, some lacking bottle cage braze-ons, and those that will never see anything clamped onto a nice frame. I've found that moving these things from bike to bike to be a real pain. Sure, they look great, but I don't want to spend $300 on a front rack, decaleur, and bag combo, on each bike.

Yes, they take some getting used to on your back, but they fit all of my vintage rides without any rattles.