I will repeat this advice from my own professional experience of those I have previously come across.
An opportunist thief normally only operates in the daylight, he or she sees an opportunity and goes for it. By virtue of it being dark on the night Madeleine disappeared I believe we can rule them out.
A burglar is not stupid. He or she will not jeopardise their own safety if there is a chance they might be disturbed. They do not rob on an ad hoc basis, each targeted property is cased carefully in order to establish who is normally there, at what time and to establish if it is worth the risk.
A burglar would not attempt a robbery if there are children in a property for obvious reasons, it just isn't worth the risk. Any reputable burglar would not therefore have attempted to enter the McCann apartment when they knew the three children were inside. They would most certainly not have used their bedroom window... a no brainer.
If someone targeted that apartment they did so as an abductor and had most probably been watching the movements there for a number of days. This is one reason why I would rule Hewlett out of the equation since he did not have the time to do so.