Macros and GAC are really two different tools in reefkeeping. It's not an either/or choice IMO.
Personally, I've never seen anything but benefits when using a quality GAC on a reef tank (I mostly use Two Little Fishies or Marineland Black Diamond). Even just running it periodically can seriously improve water quality/clarity.
Personally, I've never seen anything but benefits when using a quality GAC on a reef tank (I mostly use Two Little Fishies or Marineland Black Diamond). Even just running it periodically can seriously improve water quality/clarity.