The CHT-12 would be a definite upgrade. What is your budget and size room?
Other companies to consider would be
http://www.svsubwoofers.com/subwoofers.htm or
http://www.acoustic-visions.com/~aco.../pre_finished/ or
http://hsuresearch.com/products/
Here is a list that will give you a general idea how any sub you might be thinking of will rank out if listed?
http://members.cox.net/frankcarter/T...Sub%20Data.htm
The SVS you see on the list is a older model that is not produced any more. All their newer offerings would exceed in rank.