I use 2 11L's and a L Center with a Velodyne sub and dipolar rears for HT. They sound excellent, their mellow tonal balance is perfect for harsh soundtracks and they can play louder than you would think if you keep the bass out of them. I would not recommend the 21L's for this, they really can't go a whole lot lower in the bass than the 12's and their power handling will be challenged by deep bass and dynamics in soundtracks. Go for a sub, a HSU research is a great cheap way to get an awesome sub, I think their newest VTF-3 is around $600.
