Michael.

Adding an icon to the tool palette would be the cherry on the cake as far as I'm concerned and I can't think of a better place than the one you suggested, so it's a thumbs up from me.

Thank you.
Martin.

EDIT: This tool is also useful for creating new planes. Just create the sections as required under 'Section plane', tick 'Keep geometry', followed by 'Done' and then use the CPlane tool on this geometry. If you now press the 'Undo' button, then your solid comes back, but the CPlane stays in its new position. ;-)