halifax,
A consideration worth noting is the volume of your listening room. If it's on the smaller side then by default you will rule out the CS6 as they need a little elbow room to hear their potential.
Another consideration are amps. You mentioned bass. To drive the CS6 or even the CS 2.4 you will need amps that can push some current and Class A being at the top of that list.
Another consideration is the upgrade path you can take on xovers with the CS2.4 which Tom Thiel has been very generous with his time to help members. You will no doubt extract more performance from this upgrade.
I'm holding out for the upgrade xovers for the big Thiel's.