Owens Corning 703 vs. Roxul Safe 'n' Sound?

Thanks everyone. Home depot sells and stocks the Roxul 3" Safe 'n' Sound in a 12-pack of 15-1/4" x 48" panels for $46.27. Such a deal! Lowes sells them in the 24" width, but with a three package minimum. WAY more than I need.

Here's another question: Should I try absorption on the rest of the back wall (behind the listening position), not just directly behind my head?

At $47 for a 12-pack, you can just stack them up in the back of the room to see how it will affect the sound. They 15-1/4" are cut to fit between house frames. If you don’t mind putting up 3 panels instead of 1 or 2, it can be a cheap way to go. The Roxul are only 2.5 lb density, but they might be stiff enough to lay up against the walls. If you do this, be very careful. It is mineral wool fiberglass and always use a filter mouth mask and gloves when handling them.  There's a point where there will be too much absorption in the room.  You'll just have to experiment until you find that threshold.

The panels from ATS Acoustics are mounted in a light wood frame and wrapped with fabric. At $55-76 per panel, it’s really cheap for the build labor. Unless you are fine building them yourself.