other than looks (awesome) what is the advantage to SBR
Size and weight are two of the biggest factors. It comes into play more when the rifle has a specific purpose in which an SBR makes the rifle more capable.
If you carry it during hunts in the woods it will be lighter allowing you to carry it with less fatigue, and it will be shorter and easier to move through brush. Both factors will make it quicker to shoulder, and easier to keep on target unsupported
A SBR rifle needs a smaller case and can more easily be packed onto the rack of an ATV, slung on your back out of the way more easily, and stowed in your vehicle more easily.
If the NFA minimum barrel length for rifles was shorter than 16" I guarantee the majority of people would own ARs and other sporting rifles right at that limit.