Interesting.. CAM4 is said to give a more realistic feel, whereas CAM6 should be more convenient for desk settings.
I'll give CAM6 a try but most likely not before today's FN. I take it you hooked up the spring at the outer most connection point?
If you calibrate the rudder axis, be sure to really push the pedals to their physical limits, otherwise your calibration will be off. I'm even considering to reset it to the factory defaults, that is; using them uncalibrated.