After playtesting an Oracle (Flame Focus) through the AoW campaign, I can say that I would not recommend one to substitute for a cleric in a smaller playing group.
Pound for pound, I found no reason to take an Oracle over Cleric for smaller play groups. We have 4 players in our group, one of those being the DM.
With the limited spell selection, not even the extra spells per day or the revelations are not great enough to offset the lack of spells known. I wasn't able to overcome quiet a few situations (dealing with poisons, and disease until I could get the appropriate spells) and when I was able to deal with those problems, I lost other utility spells.
That being said, having an Oracle in a group of more than 4 players would be fine, as long as you have a cleric in the group. They would make a fine focused psuedo-warrior with some magical backup. With a decent weapon and armor selection, they could even fill in for basic fighter in a pinch.
For a smaller playing group, invest heavily in wands to use and potions to pass out when in need. Either buy them, or choose item creation feats and pour all your (as well as the group's) gold into wand/potion creation.