Just thought I'd chime in and say they're actually different measurements, and in fact three have been mentioned in the discussions so far:
1) HPS: Heals per second. Looks at the amount of healing being done over time, which can refer to a particular HoT or generally to overall healing output with multiple spells.
2) HPSC: Heals per second cast. Looks at the amount of healing generated per cast time (including GCD if applicable). This is a measurement of how much theoretical output can be provided with a particular spell.
3) HPM: Heals per mana. A measurement of how mana efficient a spell is.
I realise you may both have understood these, just thought it would be good to clarify to help the discussion
(And if you want to talk about one or another it might be good to use the appropriate acronym as above
).