I don't know about how much Defense you lose, but I calculate about 1500 Smite damage lost from those 19 points. (19*15% = 285%, which multiplied by 46 [shield base] + 400 [Grief] + ~100 [Holy Shield] gives me over 1500. Let me know if I've messed up somewhere.)
Otherwise the only argument to be made is maybe higher blocking, which isn't so important anyway. Assuming you have a fair amount of +Skills, the difference would be from +36% [1-point HS] to +38% [maxed HS], which translates to a 2 or 3 Dexterity difference anyway.
But like I said, I have no idea how to calculate Defense so I don't know how much you would lose.