I think she wanted the warmth of the pellet stove without the fuss and mess of a wood stove, to be honest. I think oil prices were a secondary driver to her decision. She's one of those "always cold" people (and so am I! Once October hits, I'm in 3 layers of fleece and wool!)
Hers is a vented stove - I'm not going to pretend I know what's going on with it or why it's not working - I leave that up to the experts.