As someone who is just starting to learn to map, I feel the Heat Maps do not provide all the info needed. All it seems to show is the most chosen place to die. Like ctf_2fort, the main 2 doors are very hot, but I wouldn't say it's a choke point. Also there is no feeling of what killed people.
The point of a heat map is to see where most activity is taking place, not to see whos not balanced. Balance in a class can be on the player side most of the times,
As a mapper you need to know what areas are under and over used and add or take away alternate routes.
Besides, Tf2 was released Oct 10th.... we are just now getting heatmaps and such so for us long time mappers this is GREAT.