That extension is OpenGL 2.1 so I think it should in principal be safe to use.
The biggest challenge in implementing hardware instancing is batching equal geometry together. I think that should be done whenever a new static mesh is added to the scene. That could bring more performance.
You would also load the material one time only for those batched objects so even more savings there.
Let’s see if we can put that in 0.5 😀