Mouseover macros improve my healing response time drastically. Maybe macros slow down some people but in my case they make a marked improvement to the speed at which I heal. They also allow me to get back to dpsing faster because I never lose my dps target by healing.

Mouseover macros are, and always have been, the optimal way to heal in any game as far as I'm concerned. But I feel everyone should go with whatever method they are most comfortable with and which works best for them.