Thanks Rowland, your considered feedback is always much appreciated
I could look at wrapping a dew heater around the focuser draw tube. However to be honest i wonder if there is much to gain in terms of tangible camera performance. As you have previously noted, there isn't a great deal of dark noise going on at 10C with either of these cameras, and regulation means that my calibration frames are nicely matched with my lights with respect to temperature (which as you know is a significant part of the battle with DSLR imaging).