In the link below there is an interesting technical interview, which could be useful if used as an indicator of the density on the boat. As of now there aint no such thing.
From my own observations and interviews another problem is that regular commuters such as me or tourist does not know where the boat will stop, whether it will stop in Skeppsholmen is usually a big confuse.
In the Slussen harbour this is the most notable information board, but it doesn't tell you anything about the route the boat is taking, it's all about buying tickets and boarding the boat. Which is totally wrong, from a human interaction point of view, as this is the most notable sign, apart of ticket purchase it should also consist of other useful facts, such as time table and the route.
And last but not least, the devices where you can buy ticket is actually directly under the sun-ray during summer times, which is a bad solution since you barely see anything.