I've got one of these and have worn it for days without problem, but then we are all different. Just ordered a Canon 70-200 F4, and now my challenge is to try and fit that in on and off camera. So impressed with the product that if the 200 ends up being too small I'll go for the 300. Love the over the shoulder design which allows for ease of camera access, but you have to wear it properly like this otherwise you do risk a slip if you just wear it hung over the shoulder like a normal slung backpack.