Conclusions:

The difference in healing is negligible, as a WHM there is no issue with the healing output of our spells. As encounters in end game content seems to trend towards spike damage, getting a tank out of the danger zone is more important than getting an extra 25 HPs restored per cure. The big help here is remembering to use presence of mind as that's when you'll see the biggest difference between the two specs (.118 seconds). Both determination and spell speed take a huge amount to see any change at all, so it really is personally preference as far as which is better. I also think that if anything square is more likely to make spell speed builds better in the future if it's not utilized much. The 2.1 changes made this better for options now with more gear having spell speed (primal accessories)