Hence my question: compared to its heating capabilities, does a heat pump use much more electricity for cooling?

In my experience, they seem to use slightly more electricity heating than cooling. I retrofitted my 120 year old home with inverter style heat pumps about a year ago and have been watching the energy use during temperature extremes.

They do seem a lot more susceptible to drafts than traditional central heat and air units; So making sure your doors and windows are sealed, and the attic (if you have one) is properly ventalated, will go a long ways towards helping their efficiency.