OK, I've just finished my commute to work and I'm sold. Pulled hard from a set of lights in DRIVE and rather than change early the car changed much later. I got a genuine surprise (bit of a shock to be honest) as the car would normally change up sooner. As a result I screamed away from the lights much quicker than normal. Overall feeling is hard to describe but in D there is definitely more urgency. It seems that a very spirited drive immediately after programming is 100% necessary because before I ran the programming procedure again I couldn't feel any difference at all.