Interesting, this may be what I'm looking for.. could you tell me how wide the bag is? It's hard to tell from a lateral angle. I have pretty beefy thighs and I'm concerned about it chafing. Also, is the velcro attachment soft? I don't want a material that's going to make marks on my frame over time. I like that it doesn't hang over a wheel so it won't get as dirty; that was always a problem when I bungee netted a backpack to my old rack. (By the way, your boxer's look in that photo is precious lol)

I like the Dynapack as well, although I'm concerned about its center of balance.. it seems like something that would possibly move around on bumpy rides.