can’t comment on the self cleaning sensor but the dust protection – ie the sealing is not in the same league as the D200 or more expensive canons. It seems to be little bits of squishy stuff stuck on in various opening doors – not a full seal around them!
Handling wise the 40D feels about the same as the 30D – the LCD is nice being bigger – its like going from the 20D to the 30D again and the viewfinder is a lot brighter.