I posted this to Nubz on skype but I thought I may as well post it here as well, someone else may find it useful:
The main objective to flow is to lead the viewers eye into the sig, through the most important aspects of it, and then out again. Currently in your sig, we can see a clear upwards and outwards trend, which would generally work just fine, but the presence of the clipping mask boxes stops the viewers eyes from naturally flowing upwards and out of the sig. Our eyes automatically stop at these points. Breaking the flow can be used well, but it hasn't been here. You see, breaking flow creates conflict within the sig, and the eye is drawn to this because it is different. But, in your sig, the conflict is created in a fairly irrelevant part of the sig, away from the focal. So they would do well being replaced with something else.