The LMS Ultra 5400 can be x'ed over much higher than that and they've got low distortion and great power handling capacity. They are 150-155 liters or 5.5ft3 each, and I use miniDSP 4x10 HD for xover and bass managment, haha. I think I told you in another thread when you asked me about Emotiva XPR-1.
I do xover @ 30, 60, 120 and 200 Hz. I'm using different settings (you can have up to four with miniDSP). I think 60 Hz is awesome, but if you really want them to be physical, 175-200 Hz will kick your chest in real hard.
Was contemplating the Class D Audio SDS-470 a while back for my 4430 actually. Let me know how they work out for you.
I'd be careful with how you wire things up, you might blow your amp if you're not careful keeping the impedance of the system up. Remember that there's a difference between actual and nominal impedance. Even if your system has a nominal impedance of 4 Ohms, it can drop below that as the impedance changes with frequency.
Classé CA-2200 has an input sensitivity of 1.4Vrms. What preamp are you using?