I'm late to the party for this crust yummy, but I've substituted half and half successfully for heavy cream. Mind you it's only in recipes for scones and a cream-of soups, but I've really noticed no difference. In the case of scones I first tried them with heavy cream, then light. Finally, when I took it all the way down to half and half, we decided that the taste and texture were indistinguishable from the high fat version to the low.
Hope this helps you too.
"Cooking is the art of adjustment". ~~~Jacques Pépin