I have chosen the Sx-46 has the readout time is much lower than the Moravian or Atik. Maybe 7secs compared to >20secs. Having used the CCD now for 20hrs in the field, the SX works fine with SGP if you ensure that you connect USB before powering the camera. I also had the camera hanging up during readout approx 3 times which might me caused by other factors though.
As others noted, the SX does have RBI preflash capabilities but the ascom implemenation for this is in an early beta stage. Actually, the person, who is writing the SX ascom driver in his personal spare time, just released the first beta a few days ago in the relevant yahoo group. The chips tempature can be set and monitored but the ability to check the cooling power usage (in %) is not available.
SX customer support is superb and fast, probably the best you find and next to the technical aspects, the main reason staying with SX.