Reduced eaves reduce the possibility of ice damming and AIUI, make it easier to air seal the building envelope between the walls and the roof. Note that that's

Reduced eaves reduce the possibility of ice damming and AIUI, make it easier to air seal the building envelope between the walls and the roof. Note that that's an air barrier, not a vapor barrier. The air barrier is pretty universally done outside of the insulation, whereas the vapor barrier location depends on the climate you're in. As you note, this does come with tradeoffs, like most things. Not a builder, nor do I have any particular knowledge of building science beyond reading Fine Homebuilding.