The Ogawa Refresh massage chair and OS-4000 massage chair are both going to give you a quality massage. They are also both packed with features. When putting the two chairs side-by-side one just seems to be a little bit better than the other, feature wise.
This first thing most people would normally be concerned about is which chair will give me a better massage? They both utilize the S-track technology, the system that follows the curve of your spine to focus on your trouble areas. The Refresh claims to be the next generation of the S-track with the Smart Curve technology. This system still focuses on the natural curve of the spine, but has more of an emphasis on the cervical curve, neck and shoulders. The quad style rollers enhance the Smart Curve technology by being designed to feel like human hands. This would give the Refresh and advantage over the OS-4000.
Little personal preferences are going to come into play. The Refresh has a smaller remote, but the OS-4000 has a wireless remote that can control the main components of the chair, when detached for the main remote. Both chairs have a spot and partial massage, although the Refresh has 3 width options. Finally the OS-4000 and the Refresh have a heavy focus on air bag technology, with the OS-4000 really highlighting the airbags, the Refresh seems to intergraded them more with the rollers, relying a bit more on the quad system.
Both chairs are going to give you a really good massage for a very long time. As well as both being quality chairs that will have specifications that look outstanding on their own. When you put them side-by-side the Refresh is just a little newer, a little fancier and going to look a little better than the OS-4000.