Flooring Tile - Joining Ceramic to Carpet

I am laying ceramic tile in a bathroom and kitchen. Both rooms meet the living room where I am having new carpet laid. HD sold me a metalic joining piece, but when the guy helping me saw it, he said I should just let the carpet lay up against the tile with out that joiner. I'd like to have other opinions on this please?

I'm with your friend on this one, I really don't like the look of the metal between tile and carpet. I normally terminate it by stuffing the carpet right to the tile, just like a wall. I'll leave the tile hang over the backer board about an eighth of an inch to give me something to stuff under, but not any more for fear of making the tile weak at the edge, If you're going straight to concrete with the tile, there isn't enough surface to the edge of the tile to stuff to and expect it to stay there so I use Z bar in that instance.