I prefer trays to grids, but am using a grid in a 5er now on an exterior stucco repaint. My biggest beef with dipping the roller in the 5 gallon bucket is that, for me anyway, it is impossible to not get paint on the sides of the roller frame. After loading my roller, invariably I drip some paint from the side of the roller onto the ground when lifting the roller out of the bucket. Not every time, but much too often. This never happens when using a tray. However, moving a bucket around outside is much easier than moving and refilling a tray frequently.