Canon 300D mirror lockup

Michael,
I agree with you to a point, I wont be upgrading the software either until I get more regular use out of the camera, and the upgrades have matured somewhat, you could always reverse the upgrade by re-installing the original firmware, if its on the web, I havent checked yet..

I wouldnt worry about dust getting into the camera as you'll have the shutter open anyway for long exposure shots, and it'll be attached to the end of the scope while this is going on, so that should be clean.
Most people would use this to avoid the vibration of opening and closing the shutter, something which I havent yey experiance with this camera thankfully, but might with more use.

As for iso3200, this just means shorter tracking times, which is always a good thing, but would this increase the noise of the system compared to a double exposure with half the sensitivity?, maybe..