Comment / #1602

I think it's a good idea :-).

Furthermore I think the problem with the hidden tasks is not that big if you also implement the customization (Show the booked efforts of a task in the task overview).

Normally the pm is the only one who is interested in the sum of efforts, estimated time etc.. So only the pm should see the extra columns and in that context your problem with the hidden tasks is solved too, because the pm can normally see all tasks :-).