Currently when a cell is placed in the model there is no way to edit the geometry by including a "cut with profile" or perform a solid boolean operation on the cell geometry. It would be very useful if the geometry was able to be manipulated without the need to drop it from a cell to normal geometry (and in the process losing it's parametric constraints). I believe it is possible to do something similar to this with OpenBuildings structural type element; it would be useful if this functionality was extended to cells as well.