The Sapphire Scientific tool is my new favorite. It out does the old style Hydramaster by a long shot. I never used the new Hydramaster so I can't comment on that. Although the old HM tool was the latest and greatest at the time it did have some problems on certain fabrics. The main thing I didn't like about it was the head of the tool was too narrow for my taste. Narrow means many, many more passes to get the job done. The SS tool I think is optimum width for upholstery work. I still keep my old tool in the van, but haven't used it since getting the SS tool. Production on upholstery is much better and results have been great so far.Seeing everyone list their favorite tools made me realize that I need to by something to be my favorite.