HPS cant be measured in FFXIV:ARR for many reasons:

- Does your target need healing? (overhealing is not good)
- Did your target used "Recieve more healing" ability?
- Are you preserving MP or do you need to go all out healing?
- Is your party member (other healer) assisting you with heals? (overheal, again)
- Many more factors to take into account.