I'm looking to buy the bayswater with strap in the sales, but I would like to know if the bag is too heavy to carry on the shoulder for long periods of time? In particular when carrying items of considerable weight (such as a laptop). Also, does anyone have any issues regarding the way the strap is attached to the bag? I'm trying to gauge how the bag is held by the strap when weight is added/it is opened, if that makes sense? Thanks guys.