We are going to buy as new garden vac and I have seen one that is 2500w which is about twice as powerful as my old one. The query I have is that my old one picks up the leaves and debris on the gravel area and leaves the stones behind, My worry is that this more powerful vac will pick up the stones aswell! Has anyone got any experience of these? Will it leave the stones behind or should I go for a less powerful one? Thanks