Not really they don't, although it might seem that way sometimes.... If a new model ( new top cap, new features, etc,) is developed they will move a predecessor to the CX series....Most models remain as long as they are popular. Of course the model numbers will change as new features are developed, so folks can decide which features they want and know the model which corresponds. Some brands keep a model number, but change the features...

I have almost all brochures from 85 to 08. Let me know if there is a particular model you are interested in... Can't wait till you join the family!!!!