The problem with the delivery guy's advoce is the word "always". Yes, anything on the three point will help counter the weight of the loader and load, but it won't hurt the tractor to do work without the counterbalance. Just be careful with the balance so you don't overturn. Weighting the rear tires helps prevent overturning, but doesn't actually provide a counterbalance - for that you need weight behind the axle. I like a 4' box blade. It is small, handy, and can be made heavy with added weight. Mine has a flat piece of heavy plywood that sits on top of the box for a workbench, some wire baskets wired to the upper link connection to carry tools, and places to place some addtional chunks of concrete and steel back there for when more counter weight is helpful.
rScotty