The main savings you would get with instanced emitters would be the savings in CPU processing, since you only have one emitter. Vertex arrays could be used to draw instances, and you would still get your main optimization this way. Vertex buffers are just kind of a detail.
You would only use a vertex buffer if you wanted to draw multiple instances of an emitter; they can actually be slower than vertex arrays if the data is updated each frame. There would be a number of instances past which a vertex buffer would be faster than an array, more than 1 and possibly as few as 2.
You would only use a vertex buffer if you wanted to draw multiple instances of an emitter; they can actually be slower than vertex arrays if the data is updated each frame. There would be a number of instances past which a vertex buffer would be faster than an array, more than 1 and possibly as few as 2.