moritheil said:
The spell isn't directly healing you;
Sure it is. Much like a wall of fire is directly damaging you. The duration of the effect is not related to whether or not it's direct. It's just not instantaneous.
it's enabling you to be healed.
Say what? How is it any more of an "enabling" effect than cure light wounds? You were always enabled to be healed, you just need to be healed. Cure light and Lesser Vigor both heal you. One heals you over many turns, the other is all at once, but neither are any more or less "enabling".
While you perhaps view it as a semantic difference, there is a difference in DnD between things that alter the nature of subjects so as to enable them to benefit from something, and things that just give that benefit directly.
And this isn't one of them. The spell does not change your status to be able to receive something. Again, any more than a wall of fire changes your status to be harmed by fire. There is nothing semantically in the spell that enables one to receive anything. It's the same positive energy received from a cure light wounds spell.
For example, the amulet of natural armor would not stack with natural armor except for the fact that it grants an enhancement bonus to a natural armor bonus (rather than directly granting a natural armor bonus.)
There is nothing similar between those two things though.
And to answer your question, it doesn't matter if it's a [healing] spell; it only matters to them if it heals hit points directly.
It is direct however. There is nothing indirect about it. Nothing ELSE is healing you - it's all directly from the spell itself. It's not like you are conjuring a creature, and the creature heals you - this is all the spell itself healing you with no intervening thing.
BTW - From the FAQ on this topic:
What effect does the Augment Healing feat (Complete Divine, page 79) have on lesser vigor (Complete Divine, page 186) and similar spells?
Augment Healing adds twice the spell’s level to the total healing it provides. The simplest method is to have the spell apply the extra healing to the first round of fast healing. Thus,c lesser vigor (a 1st-level spell) would cure an extra 2 hp of damage in the first round, for a total of 3 hit points. Each round thereafter it would heal the normal 1 hp of damage. Mass lesser D&D FAQ v.3.5 33 Update Version: 05/18/07 vigor (a 3rd-level spell) would cure an extra 6 hp of damage to each target in the first round (for a total of 7 hit points), and would heal 1 hp of damage each round thereafter as normal.