We have a DA42M in our survey fleet in Africa and it is my favourite survey aircraft. First, it has a stick and levers to ailerons and elevator so is very crisp and precise to control in turns and on the lines. Also, as somebody else pointed out, fantastic visibility in the turns, and also good ground visibility on the lines. It runs on Jet A1 which is widely available, can cruise to the survey ground at 160-70 knots TAS, and then loiter there for hours at speeds as low as 65 knots comfortably.